If your decision is to leave, unless it's a dangerous situation, I would recommend therapy. The problem for some people who decide to just leave is that they never learned how they contributed unknowingly to the situation, and how they might have saved the relationship, and then they sometimes end up repeating the same mistake in the next relationship.

Of all the people I've ever talked to who were divorced, it never ceases to amaze me of the HUGE coincidence that I'm always talking to the partner who was not at fault. It seems I never end up talking to a divorce partner who says they were at fault. And I think you could agree that when two people split up, and they both think it was good to end the relationship, and they both think the other was totally at fault, then you can understand that at least one of them is likely to go into a new relationship with a lack of insight about themselves and they are likely to repeat the problem.