Bisexual in a straight relationship..

I’m bisexual in a straight relationship. I’ve been in this relationship for a year and a half and I love him to death... but I can’t help but need a woman and yes you read that right I physically need one.. and I doesn’t help that a lot of my girlfriends flirt and lay down hints. I’m not a cheater but I told him coming into this relationship I might need female attention and he was ok with it now he is not. What do I do?