Boyfriend (27) claims that there was NO reason why he slept with his long term best friend (F; 25). Is this possible?

My boyfriend (M; 27) and I (F; 22) have been dating for nearly 2 years now. When we fist met he constantly brought up Shelly*(Name change) who was both his best friend and his sisters best friend. The 3 of them shared many great memories and moments together. I had a gut feeling that something happened between Shelly and him given how and how often he spoke about her. Shelly moved to a different country about 3 years ago and my boyfriend bought ALL of her stuff for his flat.

It came out about a year into our relationship that on a drunken night, they slept together (about 4 years go). I was initially frustrated at the fact that this information was only coming out now given that we had spoken about our sexual history several times before this and he conveniently forget to mention it. When I asked him questions about the incident my boyfriend says that there was NO reason as to why it happened. They didnt like each other, he didnt find her beautiful or sexually attractive.. "No reason". I find this very difficult to believe. I know that they were both drunk but a male needs to get hard to perform which doesnt happen for no reason. It also is very unlike my boyfriend to do something for no reason because he is a very calculated person. He has only ever slept with 3 other people. The rest of the people that he slept with he genuinely believed that that person might be "the one". Shelly and my boyfriend agreed to never tell my boyfriends sister. If it never meant anything and never will mean anything, why does it matter? (My boyfriends sister has slept with several of his friends and it isnt a issue). My boyfriend still insists on Shelly being one of his closest friends. Despite her being in another country, he has made it very clear that should he ever visit that country, he will definitely visit her... Even if its out of his way to do so. It should he be mentioned that it was Shellys first time.

This topic causes a lot of tension between the 2 of us because I dont believe it is possible to sleep with someone for NO reason at all. I also dont feel comfortable with their friendship and I feel like he is in denial. My boyfriend doesnt understand why this topic frustrates me. But he doesnt want me to be friends with any men that I have previously had any relation with (Sexual or romantic). His defense is that he never did or will like her and it happened for no reason and meant nothing which in his mind makes it okay for them to stay good friends however because I have never slept with anyone for no reason, I cant maintain my existing friendship with them. When my boyfriend and I speak about this topic he is very defensive.

Am I being over jealous/paranoid? Is it actually possible to sleep with someone (A best friend) for NO reason?

TL;DR: Boyfriend (27) claims that when he slept with bestfriend (F; 25) it was for no reason and he still insists on being good friends with her but I cant be friends with anyone I have slept with because it was never for no reason(I either liked them or lusted for them). Am I being unreasonable for being upset and frustrated about this? Is it possible to sleep with someone for no reason?

Submitted August 23, 2019 at 04:08AM by CLN79 https://ift.tt/2ZbaBiY