DerpyChest

So I am trying to understand my sis mental gymnastics. (Jk, she's just having a few loose screws).

She's dating a guy. He previously dated another girl for his prom (dunno how this info was relevant). Ex-girlfriend later broke up with him after discovering she was lesiban and moved on. He is still attracted to the ex-girlfriend.

Sis' Conclusion: She is dating a gay guy.

........And she saw nothing wrong with this conclusion. I gave up explaining what was wrong.