The Help discussion

I read a book back when I was in high school and I can not think of the name of the book, I believe it may be a book by Zane or from that era of authors maybe. To quickly sum it up to the best of my knowledge, the book starts off with a couple on the beach on vacation together and the girl eventually breaks up the guy to his surprise, the book is told mostly from a guy’s perspective and he continues to go about his life after the break up having different partners with no fulfillment, because he is still hurt about the breakup. One day while at an event he runs into his ex, who is now in a lesbian relationship, and they end up having a threesome together. And I can’t remember how the book ends and it’s been on my mind lately to know the name of that book. Thanks if anybody could help.