From personal experience even though I had issues from the beginning of my marriage, when I finally decided I had enough it had only been a thought to leave but the final issues werebwhat pushed me into action.....kinda like a build up internally till the dam breaks.
It is worth it to try to discuss going to therapy. All you can do is see what she says. Don't lay all the blame on her though for how the marriage is because that would be a sure fire no therapy decision for me & would just make my decision stronger to end it.