Can navy seal boyfriends be faithful to their GF?

I have been dating a guy for 3 months. He is also a navy seal. He seems like a great guy but when we went out a few days ago I could not help but notice that girls kind of throw themselves at him. He does nothing to deter this and one time this girl was flirting with him hardcore and after like 3 minutes he finally acknowledged he was here with his GF. Can a guy like this be faithful? I have never been insecure but the other night did make me a bit insecure.