Anyone else deal with this?

So my best friend and her boyfriend have been together for about a year and a half now almost 2 years. And I love her to death. I love them both. But I’m wondering why is it that whenever I try to get “girl time” with her, he ALWAYS has to be there. I tried to take her out to eat for her birthday and I just KNEW that he was gonna try to come. So I tried to lie and say that I couldn’t afford to pay for 3 people to come so it could only be me and her. Well he told her that he doesn’t have to eat, he can just sit with us and I don’t have to order him any food. And that he can just eat from her plate. I don’t know if I’m over reacting but literally y’all EVERYTIME I try to take her somewhere he has to tag along. She can NEVER leave the house without him. When he was working (which is rare) he told her that she can’t leave the house if he’s not home. And they live with her mom. One day I tried to have a very serious talk with her (in my car) about some things that were going on in my life . And I kid you not, He came up to the car window and asked what we were talking about and she told him that I had to talk to her about something personal. He freaking got an attitude and stomped off and later that day she told me that he was mad because I didn’t let him in the car with us .

I’ll also add that they’re both bisexual . I do think that he might not trust us alone together because he thinks we’re going to have sex. 🤦🏽‍♀️ he thinks I’ve sent her nudes and whatnot . He thinks we’ve already had sex which we HAVENT. He asked her once to ask me for pictures of my boobs because he’s always wanted to see a picture of a black womans boobs. He’s gave head to his best friend before behind her back and this was before he came out as bisexual. I’m not sure if he does this with her other friend cause I’ve never asked but literally I can’t take the woman down the street without him being stuck up her ass. I literally just want to hang out with her alone. I’m taking her to Walmart to buy her groceries cause she needs them and sure enough she has to wait until he’s home so that he can come with us. Sometimes there’s stuff I want to talk about that I’m not comfortable with him hearing. I’m not hiding anything I swear and neither is she but does anyone have a clue as to why he does this? I want to ask but I don’t want to come off as rude. I’m not good with confrontation. Why won’t he let me have “girl time” with her? WHY does he always have to go everywhere with us? Why? 😭