Husband won't have sex anymore.

I don't know where to go to talk about this with someone. I don't have any people in my life who I'd feel comfortable talking about it - so maybe I can get some perspectives here? I hope this is the appropriate place.

I've been in a relationship for 12 years with my husband and we've been married for about 3 years.

Yet, in the last few years or so (even before we got married) we've been having sex less and less. Now days, we have sex maybe once every four or five months. I always initiate and have to be very persistent before he relents. I literally cannot remember the last time he initiated sex. Maybe 2013?

I've tried to discuss it several times to learn what is wrong, and his answers are vague and hard to wrap my head around. Usually, he'll start talking about something that seems totally non-sequitur and avoidant, like politics or how we don't have enough money. I could sort of understand how those things might make him feel worried, like if I accidently got pregnant, but it doesn't explain why he refuses to have sex when those things have always been a concern, and probably more so in the past than now. I've had some meaningful conversations about how he feels about things, but it doesn't seem to solve or clarify anything. I asked several times if he just wasn't attracted to me anymore, and he insists that is not the problem.

I tell him how the fact that he doesn't initiate sex and refuses it when I do makes me feel rejected and stuck, and he apologizes and says "I'm doing everything right" but it just ends there and nothing changes. It makes me feel alone.

What else can I do? Is there even anything?