Another "weird end of a friendship" story:
Years ago I worked part time at Toys R Us. Another guy started working there...let's call him "Nick". We became cool with each other even though we were very different people: I was in my early 20s, he was somewhere in his 30s. I don't drink alcohol or smoke weed, he did so with a passion. He was a really big bulls****er and class clown type who was constantly looking for attention and constantly hitting on our female coworkers, whereas I'm the lowkey type. But dude was hilarious and he seemed to like my sense of humor as well.
Anyway at that time TRU was remodeling lots of their stores around the country. The previous year I participated in a few of them and on one of those trips I'd met this cute girl named "Candy". Her major physical flaw was her teeth...I don't know the proper term for it, but both her top and bottom rows protruded out like someone had punched her in the teeth from inside her mouth, lol. There was mutual interest but in the end nothing really happened between us. Well the remodels were starting up again and this time Nick came along with me to do some of them. Candy was at the second one we went to.
I told Nick about my previous encounter with her. He decided he was going to "hit it". Unlike a year before Candy had a boyfriend this time. It obviously wasn't a serious relationship as she flirted nonstop with both of us, but mostly with Nick. He was the more exciting one between the two of us, I guess...plus he was "fresh meat".
So a couple of weeks into the remodel I had to leave early because I was starting a full time job. Nick stayed to finish that one and do another one. Eventually Nick comes back from the remodels, and a few months pass. I was still working at TRU part time but I didn't see him as much because my schedule changed due to my new job. One day we are both at work at the same time and Candy comes up in our conversation and I make a comment about her ****ed up teeth.
Nick: LOL! I didn't care about her teeth, I just wanted to f*** her.
Me: Oh, you got with her?
Nick : Uh..nah...um...that is...
Me: ???
For some reason he thought I would be upset that he had sex with her. It was very strange. I mean we're all adults. He had a girlfriend. Candy had a boyfriend. I was an innocent bystander in all of this, lol. Yes I was sexually attracted to her too but it's not like I was in love with her. So he didn't care about screwing around on his girl but for some reason wanted it to be a big deal that he bumped uglies with a girl that both of us were slightly interested in?

I could see if she was
my girlfriend, but she wasn't. Plus she lived hours away and I hadn't laid eyes on her since I left to start my new job.
So I basically had to break down to him what I just said up above but it's like he couldn't believe me. After that he was always weird/awkward at work and we never hung out anymore outside of work.