Boyfriend issues

My SO works out of state. He is home every other weekend. When he is home I want it like crazy! He seems much less interested in having sex with me than he used to. Last time he was home we had sex a whopping 3 times and it wasn't very sensual even. More like wham bam thank you maam now make me a sandwich type of sex. Not his norm at all. Last night I mentioned wanting to do the deed and he asked "is that all you want?!" Girls please tell me what's going on with him. (On another note we are ttc)