My boyfriend is bisexual

I found out my boyfriend is bisexual. We've been together for 2 months. I found out because when I was on Facebook there was a guy in my friend request suggestions and my boyfriend said "Oh thats my ex". I was confused and asked was he bisexual or something and he said yes. I asked why he never told me and he said he though I knew because he had a picture of the bisexual pride flag on his Facebook cover when we started talking. I must be living under a rock because I had no idea what that flag was. I just thought there was only one pride flag.

He has been with both men and women romantically and sexually. I'm just wondering (I've been cheated on plenty of times) is it harder for bisexuals to stay loyal? It just seems like since they like both can they really be satisfied with just one of the sexes. My boyfriend has never done anything to make me think he would cheat, but since he likes and has been with both there is so much more competition out there....