S/O not interested in sex.

So I've tried communicating this to death wth him. Been over a year with this same issue. I've offered to change anything about myself that would make me more appealing more interesting to him. Every time we have this conversation he assures me that it's not me it's him...That he's stressed or depressed or worried about money. This stress or depression doesn't affect the rest of his life in anyway. It leaves me frustrated, insecure, and feeling like I am unattractive. He's incredible. Loving, kind, affectionate otherwise - but passion is a huge part of a relationship for me. An aspect of a relationship that I need.

The topic is causing a divide between us and is the root of the tension and most arguments that we have for obvious reasons. I feel like he's not letting me in on the secret of what the problem is. All I'm left with is insecurity and unfulfilled needs.

I'm considering walking away. It's a really tough decision because as I said he's a great man otherwise but it's not healthy for me to continue living like this. Living with a huge void. feeling like something is wrong with me. Like I'm defective.

Any insight/advice/experiences would be appreciated. Thank you in advance for any kind/helpful words.

Ps. We once had an exciting and incredibly passionate sex life. So I know it's in him & he knows how much it means to me bc he met me this way. Thought that was important to include.