jealous

Help! I'm starting to get jealous of my really good guy friend who I've been doing friends with benefits with 😬 I'm terrified that he's getting closer with this girl he's just met who hangs out with us a bit.  I know it's a bad sign but I need advice on what I should do! We've been really honest and open up until this point and I'm scared he's going to think I'm crazy! What should I do?!?