Erich Segal sat in his suite in New Haven last Saturday night pondering the Harvard-Yale game. "That game is schizophrenia time for me," he said, reflecting on 11 years as an undergraduate and teaching assistant at Harvard.

The author of a phenomenally successful novel, "Love Story," Segal is now an associate professor of literature at Yale. But when Harvard and Yale line up Saturday in Cambridge, Segal will be far removed editing a new film in California.

The nerve-racking duality of The Game reached its apex for Segal two years ago when he came to Cambridge for the meeting of unbeaten Harvard and Yale teams. It was his last football game.

Segal found himself sitting in the Yale faculty section that day, but he ended up cheering for Harvard-for a moment. He was soon quieted by an older, more mature member of the Yale faculty.

"God, I was sitting there and all of a sudden I started screaming for Harvard," he recalled. "Then this professor sitting two rows behind me comes crashing down with his umbrella."

Segal's skull was saved by a mathematics professor sitting next to him who blocked the umbrella with a cushion. Not entirely undaunted, Segal spent the rest of the afternoon serenely observing one of the most blood-curdling comebacks in football history.

"I will neither sit in the Yale faculty section nor go to any more football games," Segal said Saturday. "I mean I was Jo? Massey's Latin teacher and I like to see the team do well, but I have a lot of ties with Harvard."

Segal graduated in the "noble class of '58," as he put it, then stuck around to get his Ph. D. in comparative literature. As an undergraduate, he was a runner on the cross country and track teams.

From 1958-65, Segal was a section man in Hum 7 and Hum 2, and he was Professor Harry Levin's head

section man in English 123 during his last year at Harvard.

"Levin really cares about his students," he said. "He's a magnificent teacher. And Finley (who taught half of Hum 2 at the time) is one of the reasons I'm in classics. I've never heard a better lecturer than Finley on 'The Odyssey.'"

After spending most of the past five years in New Haven, Segal shys away from comparisons between Yale and Harvard. "I feel detached from Harvard," he said. "Yale is more isolated, but there's a real spirit here in the colleges, and there is a belief in the University as an institution.

"There's been a huge change at Harvard since '68-there's no joy in the air. It's a quiet despair, but it's not even quiet. Harvard guys, nice as they are, have always been smug as hell. But even the usual smugness seems to be missing."

The first time I saw Erich Segal was in the courtyard outside of Yale's Stiles College, where he is a Fellow. It was a passing view: he streaked by in track gear, wearing a wool cap and a blue plastic vest with orange reflecting panels.

At the end of nine miles, he was sprinting strongly. No wonder-Segal has competed in 14 of the last 15 Boston Marathons, usually finishing in the top 90. To keep in shape, he runs about ten miles every day despite a routine that would frighten most leisure-worshipping students.

Segal, who is single, lives in a suite that was last occupied by a Fellow, his wife and their two children. Segal needs every foot of the space-he simultaneously teaches three courses at Yale, meets a harried speaking schedule, edits motion pictures, and writes.

Segal is ecstatic with his constant activity. At present, he is trying to finish The Death of Comedy, a comparison of classical and modern drama.

"I owe somebody something here at Yale after my ego trip with 'Love Story,'" Segal explained. Surely, his recent notoriety has resulted primarily from that novel, a short, unimposing book about a Harvard jock-scholar and his Radcliffe sweetheart who dies at age 25.

Sunday, "Love Story" headed the best-seller list for the 29th consecutive week, a new record. And yesterday, the largest single printing since the invention of moving type-4.5 million copies of "Love Story" in paperback-became available for public consumption.

"'Love Story,'" said Segal, "is an amalgam of truths. It's almost all true."

The idea for the book came from several Yalies at the Harvard Law School who visited Segal on Thanks-giving two years ago while he was living in Dunster House on a Guggenheim Fellowship.

They told Segal of a classmate whose wife had recently died, and that she had supported him while he completed graduate school. "When they left, I was struck by how the guy could ever have a relationship again considering when she died and how."

Segal built his story around what his Yale friends had told him, drawing on his years at Harvard, and he wrote the book that winter in Dunster.

Among other things, Segal said, "Love Story" is "a distillation of four years of road trips to Dartmouth with the hockey team, listening to them talk about size and eating and so many things that don't occur to other people."

It is about Jenny ("she's like a girl I went with once") and Oliver Barrett IV ("who closely resembles a friend of mine at Harvard").

"'Love Story' is really a little valentine to some friends at Harvard," Segal said. "I never expected it to be so successful. That it got published in the first place surprised me.

"There was nothing in the balance for me. If it was no good, what the hell? If it was published, it would implement my income."

That has turned out to be a mild understatement. Segal has made enough money from the book, which has been translated into 20 languages thus far, to retire "several times over."

Some of his colleagues at Yale have even suggested that he endow a library of comparative literature.

The response to "Love Story" has been unusually good, except in England where the London Times called it "the death of the novel." "I was critically damned in England," Segal said. "I mean I was trampled." Nonetheless, the book sold widely.

The literary welcome offered Segal in France was just the opposite. There he is "the new J. D. Sallinger," and he has risen to a plateau just below one of Homer's Greek gods.

Segal admits that to fully appreciate "Love Story," you have to have gone to Harvard. And yet the simplicity of the story has universal appeal. "The little jokes don't really matter to the story," he said. "When it's translated into Korean, there's no end to it."

The New Statemsan once reviewed "Love Story" and declared Segal "sexually anemic." "I just couldn't gross myself out by writing a love scene," he retorts. "If anybody asks me about Oliver and Jenny, clear out. They can check out Irving Wallace and he'll tell them."

The strength of the book, Segal likes to think, is not what is in the book, but what is left out.

"Love Story's" effect has been widespread and varied. Albert Gordon, the chairman of the Harvard College Fund, liked it so well that he sent copies of the book to 593 major donors with best wishes.

Many people feel that "Love Story" has done more to bolster the alumni'sfaith in Harvard than any single thing in the last decade.

But undoubtedly one of the more bizarre incidents involving the book occurred earlier this fall.

As the New York Giants football team was leaving for Boston to play the Patriots in Harvard Stadium, writer Dick Schaap gave a copy of "Love Story" to Fran Tarkenton to read on the plane. After sobbing through the last three chapters, Tarkenton passed it on to his roommate, a mammoth lineman. Same result.

After the book had circulated through the squad that afternoon and the night before the game, with predictable results, Tarkenton telephoned Schaap and told him that the book was "destroying the team when they were supposed to be getting psyched up for the Pats."

Last Saturday night, Stiles staged a "Segal Marathon," which consisted of two films for which he wrote the screenplay- The Games and The Yellow Submarine -and out-takes from the movie, Love Story.

It was an appropriate juxtaposition. In The Games, Ryan O'Neal-Oliver in Love Story -plays a Yale distance runner who ends up collapsing into a concrete monolith during the Olympic marathon.

Then in Love Story, which, judging from the out-takes, is certain to be a real tear-jerker, O'Neal plays the preppie hockey star from Winthrop House.

Yale-Harvard, Harvard-Yale, it all returns to The Game. The difference? "Obviously, the difference is that Harvard men are better looking than Yale men, or vice-versa," Segal mused.