[M18] I am very close friends with [F18] and she is obsessed with a boy. How can i tell her to stop talking about it around me?

I am best friends with a girl. We go out to dinner a lot, talk all day at school, study together, etc. As you can see, we are really close. Being a guy, its hard for me NOT to catch feelings for a girl I am this close with. Ive been able to pertain them for our friendship, but she keeps talking about this guy shes in love with. I just so happen to be friends with that guy. Anyways, she talks about him a lot to me and it really annoys me. I cant tell her I like her because it would ruin everything, but hearing this always makes me jealous. I keep telling her to stop talking about him around me but Im not sure if she understands. How can I tell her to stop without showing my jealousy?

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tl;dr Girl I am super close friends with that I will always have feelings with but I know she doesnt like me is obsessed with a boy. How can i tell her to stop talking about him around me without showing that im jealous?