This also happened to me and my husband back in college. I had a difficult time with the social aspect of my major- this one guy I'd known since high school would just ride me in the small classes we shared- getting other people to gang up on me and reducing me to tears in class more than once. I managed to get to senior year but was not well liked (and in small, like 6 person 3-6 hour long classes that was tough).

Then we went to a party- it was my senior year, and included my then BF, with my classmates and the guy who was so inexplicably nasty to me.

He walked up to my husband and was like "I'm so sorry dude, I forgive you." My husband had no idea who he was- that he was the guy who was brutally nasty to me for four years or anything. Dude explained. Rude boy's first love, whom I had known well in HS too, had dumped him. Because she had a new boyfriend, my husband (according to her). And (still rude boy's point of view) then my husband dumped her in turn, to be with me, and I was the instigator of the whole thing and encouraged my now-husband to break her heart. And rude boy was left with an ex he dearly loved who had to see this girl's heart ripped out and tromped on by me and my husband for fun.

Except it never happened. She met my husband twice- once when they climbed a tree with a group of friends and once when he went somewhere in a big group with her and some other friends. And she invented this whole terrible scenario starring me and my husband as gigantic ass holes. We barely remembered interacting with her, either of us, ever.

I ended up avoiding the field I studied in college for the last 15 years and rude boy is internationally famous and successful in it. No idea what happened to the girl. I'm at least successful in a different career.