Reduce sex

Hello my boyfriend is 40 and I'm 29. We've been together for 6 1/2 years. In the beginning, we was having sex a couple of times a week with multiple rounds, and that was awesome. Over the course of the relationship, however, we have been reduced to once a week. We don't live together as I still live with my mom until I graduate college (please don't laugh) and I've become stable to be on my own. His work is very strenuous and it requires a lot of his time Monday to Friday.

So when we finally get a chance to, we enjoy every moment. It just bothers me that we don't "do it" as much as we use to.

Should I be concerned about this?