Most Helpful Guy
dont let it change anything. If he still likes you then what is there to worry about! I say you should just thank him for being honest and talk to him about it :)
Most Helpful Girl
If you love him, does it matter that he's attracted to boys and girls? Sure, it might be easier to get jealous, but at the same time, it shouldn't change your relationship. He shouldn't be cheating, straight or not, so you shouldn't really feel like there are more opportunities for him to cheat if he's bi in the first place.
A lot of people are bi, and several don't even admit it. If you like him, it shouldn't matter as long as he loves you and only you. :)