So we're chatting on facebook. Seems interested, responds quickly, accepts sexual jokes etc.

Today I asked her for coffee and she said "my bf will get mad hahah". Then she started explaining herself saying that she's a very communicative person, that she wants to make friendships, that she doesn't want to isolate herself from guy friends blabla...

They are only 3 months together and they are kinda LTR, seeing each other once a week.

So, I think she is thirsty for another cock but is afraid of slut shaming. What should I do next?

I am 24, she is 20.