I 26M and my wife 25F have been married for 6 years and poly for 3. My wife has had a few dates in the past but nothing has worked out until recently. I am currently away from her on military orders at the moment. But she is planning on having her first overnight date with him tonight and she will most likely sleep with him. I am 1000% happy for her, knowing that she is able to be loved when I'm unable to give that to her and knowing that he makes her happy in addition to me. I'm just nervous because I was my wife's first and this is will be her first sexual experience aside from me. I hope it goes well for her but I'm just seeking advice for a few things....

What is the best way I can support her if it goes well, or if it goes poorly? For anyone else who may have been in this same boat, how did you want to recieve after care from your main or primary or other relationship?

Also, Today is her birthday, and we talked about always spending holidays together but she already planned this. And yes we did talk about that and that it bothered me that she would rather spend her birthday with him. But I told her I want her happiness and her day to be enjoyed in whatever way she wants so we did have communication as to it bothering me like that. But what is something I can do for myself to help with this transition and realizing that she is no longer solely mine in that regard? And aside from telling myself to be happy for her, what are some ways to distract myself from worrying or feeling bitter that it's him and not me on her birthday?