My husband recently brought up that our sec life frequency is really bothering him and that the ebs and flows of it are “really difficult for him”

Now little background- I work full time, take care of our 3yr old and the house. He works as well &is in graduate school getting his second PHD. So needless any time spent together is limited & usually used for the little one. He typically goes to work when I put the little to bed then half the time doesn’t come to bed until after 2am or falls asleep at his desk.

Please tell me that there’s other couples out there that go through varying frequency of sex. I’m definitely trying but staying up until 2am when I get up at 5am isn’t an option lol.

Help! Thoughts? Tips?