Why do I repeatedly experience betrayal from other women in friendships/& in family specifically involving them crossing boundaries with my partners?

Why do I keep experiencing betrayal from other women in friendships? Every time I’ve had female friendships, I’ve noticed a pattern where some of them crossed boundaries with my partners making a move such as flirting, sending inappropriate messages, or even becoming sexually involved with them behind my back while knowing I was in a relationship. And I know my partner is part of the issue for allowing it and let it continue without telling me. They’re an ex atp but the point still stands. I just want a boyfriend and a group of friends by my side but it always gets messy. I am not sure if it’s a competition thing but It consistently happens after I share identifying contact information about my boyfriend or any guy I start to get interested in like his name, what he looks like, his social media, or his number so that my friends can recognize him when I talk about him.

This has happened multiple times in my life and it’s made it extremely hard for me to trust other women or feel safe forming close friendships. I experienced this all through middle school, high school and college. I even experienced this from my sister and my own mother who’s almost 60. She would involve herself with the guy I would tell her about, find his Facebook, get him to flirt with her and ruin the whole thing. She shown me the messages I guess to hurt my feelings. My sister on the other hand is the same, while they had a boyfriend I would talk to them about a guy I was interested in/talking to and I found out through their phone they were flirting, sexting and hooking up with the exact guy I just told them about prior. They never do this with guys I am not into. Either we have a type or they can’t find a guy elsewhere and purposely do this despite knowing that. For their relationship with their boyfriend apparently it was on and off so they mess with guys in between? I wish I was lying but this is true. What can I do in the future? I’m 21 now, been dealing with this since I was 15.

Why do I repeatedly experience betrayal from other women in friendships/& in family specifically involving them crossing boundaries with my partners?
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