I miss my bf more than he misses me

My boyfriend goes out of town for 1-1.5 weeks at a time pretty frequently (like once a month for the past four months), yet he doesn't ever seem to be as upset about leaving as I am. I'm used to seeing him pretty much every day so I always get super sad during the weeks that he's gone. However, he has never really seemed sad or upset at all about it. I often tell him that I miss him, and a lot of the time he doesn't even say he misses me too. I just feel like I care more about being around him then he does. Is it normal to be so sad about a SO leaving for a week/week and a half at a time, or am I just overreacting?