Welcome and thanks for posting
With him being four months sober, the entire fabric of your relationship has changed, he's changing, and if you are "doing" recovery rigorously for yourself, you will be changing too.
A few things I have learned are, if you aren't growing together, you are growing apart, now what is happening now may or may not fit this criteria.
In my experience, after one or the other partner gets sober, you literally have to 'start over" and relearn who each other are especially since there is so much change that accompanies sobriety.
Quite often it looks exactly like what you are going through right now, they say "relationships take work" this is what "they" mean, and it takes two people to work on a relationship, so, for me, if I am idle and apathetic, I can't be too surprised if the relationship fails, and the flip side, if I am the one doing all of the "work" I'm not too surprised if the relationship fails, it's just I have a little more control of the outcome of option "B", not much, but a little.
Anyhow, for me, I notice I seem to have much better results in every aspect of my life if I put my own recovery first, especially my relationships with those around me, kind of "you can get more bee's with honey then you can with vinegar" and that way if it doesn't work out, you will know it wasn't you, and that you couldn't have done anything different, because you have done the best you could.
In my case, I got sober and the two of us worked our programs for a few years and after about five years we realized we didn't really have anything in common, or the real basis of a relationship, once we removed the "dysfunctional" parts of the relationship, it turned out that's what the entire relationship was based on, kind of like throwing the baby out with the bathwater.
Things like this make sleeping at night easier if that makes sense, getting a sponsor and working my own program covers all of these issues.