SO is always horny

Kay
So my SO and I go to the same college. On Tuesdays and thursdays I have a three hour break between classes. So yesterday (Thursday) I got my period and I always feel extremely terrible. I'm extremely tired, cramps, body aches, etc. So he picked me up from school and we went to his house. I took my shirt and shoes off and got into his bed with just a bra and my leggings and he got into his bed shirtless as well. He was running his hand up and down my back to my butt and I fell asleep. When I woke up he said "I don't know how, but you always manage to turn me on" and I was like "what did I even do? I was asleep?" And started laughing. 
Does anyone else's SO get turned on so easily?