Am i a crazy girlfriend ?

Been with my bf for almost 3 years (22-23) we work full time at the same place for almost 2 yrs at a big retail store with various departments. (Even though we do work at the same place, we barely see eachother at work) He claims that he met his “best friends” there who are both girls. (Those two girls are best friends since middle school.) Anyways one of them works in the same department as my bf but i dont really care because she has a boyfriend now and i know my bf only sees her as a little sister. All 4 of us would hang out 2-3 times a month but i would always feel jealous or not included. Maybe because of their close relationship with him. I feel out of place because i’m not close to them. His other “bestfriend” from his department been MIA lately because she has a bf right..

so its only been the 3 of us (the other bestfriend, me n my bf) but when we do hang out i feel like i’m the one third wheeling them. Like he even does his baby talk to her when i thought thats only for me??! He just doesn’t know his boundaries when it comes to those things.

in addition, she recently been seeing and talking to my bf’s cousin who she met thru my bf’s bday party. Anyways theyve been talking for over a month now but ive noticed my boyfriend seems jealous over them. Asking her what

they do after they hang out n other personal questions like some uncomfortable questions.

I already told him this and how i feel. But he just keeps defending himself and not acknowledging my feelings.. says “its more fun with them” so what does that mean? Is he losing feelings?

also when i do make plans for the both of us, he would always be like “okay only until this certain time okay?” Or “i have to do this later” But when its with other people he wants to hang out until whenever. He only makes plans with me when he wants to hang out with other people. I’m the only one who actually tries and puts effort into this relationship.