Sex once a week 😭

My boyfriend and I have been together for now 4 months but I could probably count the times we’ve had sex 😭 I love it when we do, it’s mind blowing which makes me want it regularly but he’s just not up for it.

Any advice on what I could do to get him to be open to it more often? Oh and we’re tired from work during the week but surely that can’t be an excuse.