So much of your story is similar in so many ways to mine. I noticed immediately, though, when my H took off his wedding ring and it felt like walking into a brick wall. He said it was "time" which I later realized meant he was interested in someone else. I have this strong feeling that your H wants to go to Germany without wearing it and is looking for a reason. But I'm usually wrong, so I'm sure I am this time too; in fact I hope I am. When does he go? I feel lousy for you knowing he is spending his birthday with OW. That hurts. Still, for most of the time she is half a world away.
The bad thing about that is he doesn't get to see her in all her moods so he can build her up in his mind to something and someone that she isn't. That's just fantasy; not reality. They never seem to get it.
I'm not sure if your initiating R talk is good or not. I certainly understand your wanting to because I am the same way. Let's just get it out on the table and then we can deal with it. I NEED TO KNOW. But he would tell me that I don't need to know. Used to drive me crazy! But looking at it from his point, I think he might see it as pressure from you, asking him to move back home. And from his answer, to me, it sounds like a well-I-am-not-ready-but-I-can't-tell-you-that-right-now answer. So he kind of put it off by saying sometimes he thinks about it. Still, you know him better than I do!