I think my boyfriend is gay

My boyfriend is bi and has admitted this, but recently I've has suspensions that he's gay and not bi. He always asks to do 'butt stuff' with me and wants me to do 'butt stuff' with him. Hes done stuff (not s*x) with a lad a year before we met. Hes also really comfortable around other males, he kisses, hugs etc with his friends as a 'joke', saying 'love you' to them. We only do intimate stuff about once every 2 weeks and we kiss but we don't make out anymore. I've asked him if he's gay and not bi but he's saying not? Idk what to do, we love each other but if he's gay I don't want to hold him back, I want him to do what he wants to do.