It's perfectly normal to have a lot of sex. What matters is whether or not YOU feel it's too much. If you feel it is, just spend some time doing other activities you enjoy together and building intimacy in that way as opposed to through physical contract.

I usually have sex four times a week between both my partners. I see each for one to two days a week, so that's about sex once, sometimes twice per day with each partner. And this is after being together for three years and a year respectively. So yes, it's perfectly fine to be having a lot of sex even after being together a while.