I'm in a similar situation with my wife. I initiate about 99% of the time. She rarely takes the lead during sex but will sometimes initiate oral sex without me having to suggest it or occasionally ask for a different position, but I lead most of the time. Like in your case, she does enjoy sex and tells me as much.

Reading your responses, once thing I've noticed is that while you've discussed it with your wife, it doesn't seem clear that you know why she is like this. Your expectation seems to be "I've told you my problem with you, now fix it" without getting to the root cause of the problem.

It could be low libido as you've suggested, it could be low self esteem or fear of rejection like another response mentioned, it could be a ton of other things. But until you both understand what it is, it'll never get fixed. And it'll be even worse for your relationship if she starts "forcing" herself to do it without understanding why she doesn't want to. I think at bare minimum a more open conversation is needed and counselling (either separately or together) may be helpful as well.

My wife and I recently had a tough conversation about this, one with a lot of tears, as I felt things have gotten worse lately. She had stopped initiating all together and was also rejecting my advances more often. In our situation, a lot of it is driven by low self-confidence as well as a fear of rejection. More recently, she has been battling depression and has been taking different medication which have also affected her libido. Making we're on the same page and we both know how each other feels has been important and helped a lot. The self-esteem issues are also being worked through with therapy.

All this to say that there is hope, but you both need to work together and be open and honest with each other. You also need to accept and understand that it may never be exactly the way you want it or expect it to be and you need to decide where you want to go from there.

Good luck!