Hmmm. It’s happened to me three times. The first time, I desperately did not want it to happen, but she did, and she used my graduation as a way to do it, and it took me years to stop loving her.
The second time…. I think I slowly learned that she wasn’t the quirky person I thought she was. Or that her quirks were different from the ones I liked. My cock kind of died first. I was no longer interested in her sexually, and that showed me that I didn’t feel a good connection to her any more.
The third time, it happened over a long time—a year or more. She was from a different background than I was, and had many different ideas about how things should be, or reactions to various things. Again, we weren’t really connecting any more. Again, I slowly stopped being interested in her, sexually, and finally, I met someone else.
I’m still with that someone else, and have never stopped loving her, and don’t plan to. We’ve had our problems, especially lately, but we’ve taken steps to fix them, and it is really helping us fall back in love.