Hurt, I think you are more in a continual transition with your feelings than being a yoyo. Reality is that on your journey of detaching you are going to take some steps back as you keep moving forward. From LH's questions with which I agree, there's still a fair bit of you seeking W's approval and/or some covert contracts like if I do this, she will think/do this and the text reply in which you reference the emojis she used, that comes across as some hopefullness/what did she mean by that type feel in your mentioning it. Bottom line you are not going to go full stop from attached to detached, just some ways/things that you are doing/saying which show you still have further work to do. Time will help that. Don't beat yourself up on being a yoyo, you will go up and down as you go along and that's normal. Main thing is you recognize it and as you do work to get back to the positive side of detaching and moving yourself forward.
The impact of children on a marriage, for sure that can be a HUGE factor for many of us. I know for a fact it was in my sitch. I think there's the real aspect that motherhood and it's demands can have a huge and sometimes negative impact on our wives. I know mine felt tremendous stress and worried about failing and had lots of anxiety as a result. When I read of your wife worrying that she wouldn't hear him with the baby monitor on, that resonates with me. Was moving the mattress in there soley a result of that concern of her's or was it a convenient excuse to conceal deeper issues she had in the relationship, who knows. Thing is as I've learned in my sitch, many times it is very hard to see how something in the past done with the best of intentions could end up manifesting itself as the cause of problems in the future. You can't change the past and seemingly that was all done with the best of intentions so as to take care of your S1. Just don't beat yourself up over it.
Lastly, enjoy D4's birthday party. Be sure to soak it all in and take lots of pictures and video. Whenever you find yourself yoyo'ing pull those up and watch/look at them. That is the "good stuff" of your life now. It will keep you going on the right path no matter what your W does.
