Happy All the Time by Laurie Colwin

Vincent is pretty certain he will win a Nobel Prize for Physics. When he meets Holly, her loves her on sight. Guido plans to write poetry and when Misty - bored and misanthropic - steps into his office, he finds himself desperate to know her. Through courtship, jealousy, estrangement and other perils, we watch as the two couples manage to find love in spite of themselves.