What woman reaches orgasm with sex? Very few. Much less every time.
Learn to pleasure yourself and then share your knowledge with him. Men need direction but are often afraid to ask for it.
Maybe he set a standard and cannot keep it up anymore. (NO pun intended.)
How old is he?
Stress. The kind of job he has.....yes, even gay..but doubtful....although who knows?
Lots of men, even young men have issues with erections. Getting them and keeping them alike.
Three or four times a month is not bad. There are lots of people not having sex that much with their spouse.
The longest I went while married was 14 days. And that was because we were fighting.
It is not normal, per se. Five months into my marriage, I was five months pregnant. We still had sex about 1 to 3 times a week. His work was a problem and he has chronic fatigue. Still we managed. I will admit to always wanting more myself.
Talk to him about it and tell him how much it is bothering you. Find out the reason why. Let him know you are serious about it.