Yes, it has happened to me. I didn't know whether I loved her or not when I was with her, but after she ended things I quickly realized that I really did love her. I guess the saying of "you don't know what you've got till it's gone" is accurate in my situation.
My ex did this to me. After breaking up with me, dating somebody else for over a year, two years on she tells me she has never fallen out of love with me or been able to move on. Why she wasted two years to tell me this (when I was madly in love with her) I'll never know but by the time she did confess I had moved on and didn't feel the same anymore!
I don't think it was too late when I really understood my feelings but things were so bad. I've been rebuilding for over 3 months and its a lot better but can be rocky because I'm still mad about infidelity that happened at our worst moment.
i realized I'm in love with my best guy friend 3 days ago. He went Facebook official with someone else a day and a half ago. I can't stop crying, I'm heartbroken. So tell people how you feel because the pain of not is definitley way worse!