Hey /adv/, I am a naive faggot?

I feel uncomfortable when my girlfriend talks about her exs. It can be when we're alone or with another people. I don't know what to say, how to react. I suppose girls want their man to react about the subject. But sometimes it kind of hurt me, even if I rationnaly handle this.

I suppose it's because she's my first girlfriend, also she's the first person I really love with all my heart. But I want to appear as a man, not as a slug with emotionals insecurities.

I suppose it's easy when you already had lovers in your life. Please explain me your point of view.