I think you commit to trying and stop leaving the "door to divorce" open or you just agree to divorce. In my own relationship, we never, ever play around even half-heartedly with the idea of leaving each other. If it were necessary, we would, don't get me wrong. Neither of us would be one to stay in a crap relationship, but it's the use of the idea of leaving as an out that's dangerous. I think it keeps you (not you yourself, but the royal you) from trying, really trying, and keeping things real with each other. We've actually, verbally, agreed with each other than neither of us will ever joke about it, nor will either of us use it in anger against the other. I actually think it's a really powerful thing. In your case, there IS a point where you sit down with each other and say "this really isn't working and we're really done trying" but that's a decision point that you've yet to get to. Until then, the option needs to be put away (in my opinion).
I have the weirdest problem. I garden, a lot. Sometime a month ago I stuck my right arm into something that made me itch like crazy (just my forearm). It hasn't stopped! My doc says I need to take an oral antihistamine to get rid of the itch, since my body is a little crazy and reacts systemically sometimes to topical issues. But I hate taking stuff when I'm pregnant. But I CAN'T take the antihistamine after baby is born because it can hose milk supply. So I'm going to take it this week. Weirdness.