Valentine's Day

He calls me his girlfriend, but never asked me the big question?

Kay, so I've been seeing this guy for about a month now, we're both in the US Army and both serve in the same brigade, his barracks building is actually directly across from mine, so we live extremely close to each other. We hang out a lot and have been intimate. Well this past weekend (we had a four day weekend which means we had Friday and Monday off) we spent it together. From Friday (which was Valentine's day) to Monday we spent it together, the whole time and we stayed at a friends apartment and had a lot of fun. He refers to me as his girlfriend. He tells his friends or any new person we meet I'm his girlfriend, he calls me babe and stuff, I've met all his social circle and also his team leader and squad leader (army talk) he actually introduced me to his squad leader and said who I was and that I was his girlfriend. My question is why did he make it exclusive without asking me? Why didn't he ask me to be his girlfriend and just put a label on it? It makes me confused and makes me wonder, since ever guy I've ever dated has asked me instead of just automatically making it exclusive, any help would be great thanks!
He calls me his girlfriend, but never asked me the big question?
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