LGBT: Came out to my boyfriend... he doesn't want to end the relationship?

My boyfriend knew before we went out that I was "confused" and hated the thought of being gay an that's why I went out with him. Since being with him I've had my first experience and it gave me feelings I never knew I had, just kissing a girl gave me erflies and that's never happened before. I knew before that I had feelings for girls, I would check girls out not lads. Are relationship has been on and off because of my confusion and I didn't want to have to brake up with him again so I told him about the girl and told him it brought back all the feelings I had before and his reply was "I don't want this to end" then abit after it was like I never even told him, he was just acting normal like I'd not just dropped a mive bombshell. Why would someone do that? How could he not of broke it off knowing I'm gay he's acting like i never said anything, I just need help to understand his behaviour, thanks for your comments :)