Self conscious 😒

My bf and I have been dating since August and I’m very sexually attracted to him and he says the same about me. However, we never have the house to ourselves because there’s always someone home. So we are in my car and things get heated and I’m thinking we are finally going to have sex but then he says he can’t get it up. I was so embarrassed and felt like he wasn’t attracted to me and we just didn’t speak about it. Then another time we went out the same thing happened and he was like I’m sorry I don’t know what’s happening I think it’s because I’m too big and the car is small. He’s 6’2 and I have a Honda Accord so I thought i might have been dramatic but then a third time came and he still couldn’t get hard. I love him and he’s really an amazing guy , I’m starting to think he just isn’t attracted to me and it’s starting to get to me 😕. Has this happened to anyone ?