Honestly, I'm not one for ultimatums, but at this point it seems like you have done everything to try and communicate but you can't go any further if he won't put in his half of the effort.

Perhaps it's time to tell him that it's time for therapy to help fix this issue or else you're done. No more of this, "I'll try and do better but I don't want to go to therapy with you" nonsense. He either goes or you go.

Especially since by the sounds of it he isn't providing much in the marriage or bringing anything positive to your life. You don't have to stay with someone and be unhappy. It doesn't have to be extremely toxic and abusive for you to leave. You're allowed to leave because your needs aren't being met and you aren't satisfied or happy anymore.