Redditors who have been cheated on, what was their (dumb,unbelievable, "I'm sorry,what?") reason for having cheated on you?

My ex happens to look a lot like a character from an extremely popular BBC TV Show. He cosplays that character regularly as the resemblance is uncanny. On one occasion we were maybe 3-4 dates into our relationship, a weird girl at one of his conventions spots him and basically launches herself on him. The next day he goes, she's brought him homemade gifts and chocolate. He tells me how weird and creepy she is, and I'm pretty confident nothing happened as we were early on and why on earth would he do that with someone clearly very creepy? I found out maybe 4-5 months down the line from his best friend that yeah, he did take the creepy girl home. He slept with her the same day he slept with me, in the same bed. He later said he didnt think we were serious at that point and he didnt want to tell me as he 'regretted it anyway.'

/r/AskReddit Thread