What is wrong with my SO?!

Katie. • 31 mother to two amazing boys, 8 and 3. I also have an amazing step daughter who is 19.
Does anyone else's husband or SO tell you he's too tired for sex?!?! I've never had a guy tell me that and whenever he says it, I want to barf and punch him in the face. 
We are TTC so I feel like he doesn't want to do the deed as often as me bc I'm purely baby making over here. 
Can anyone relate?! :(