Sex once every 3 weeks.?

Hi I'd like to know what yall think. I'm a married 35 year old women. A stay at home mom. Have a three year old son. My hubby works 6 days a week to keep us afloat.

He works hard. As do I at home , with our son.

So he doesn't sleep with me. Comes to bed much later than me. Doesn't initiate sex. Doesn't hint or flirt. Doesn't like it when I try and touch his penis or rub it. He says he is tired. I asked what's up, he just said oh no , not now the mood not right. But my mood is right. I know he is tired. I cook clean and get our son to bed by the time he comes home. He doesn't want much sex. One time in a month maybe he will just put it in wham am thank you mam. He is not cheating I keep a track of stuff and him. I'm not as hot as I used to be. But can still look ok. Why this rejection.