Advice please!

Hey there Glow ladies. So I have developed a very strong attraction to one of my boyfriends best friends. My boyfriend and I have been together for 8 months and we are doing great! Also the one I have a crush on has a girlfriend, but she has cheated on him 3 times and he has indirectly expressed interest in me to my boyfriend about a month ago. I wouldn't do anything to compromise my relationship, but he is really really attractive. Help!