Hi and welcome
May I ask exactly what you find so wrong about her going on vacation?
I doubt your feelings are related to finances as the trip is all expenses paid and her time off work is paid as well.
So I am just wondering wherein lies the problem as you see it?
If you don’t mind I will help brain storm... ( Something I do personally when unsure of the root of an emotion)
• Do you feel incapable of running the household without her for a few days?
• Do you feel upset that she’s out to have a good time while you’re stressed out about finding a new job?
• Do you feel insecure or jealous that she will be gone without you?
• Do you not trust her to go away for a few days?
• Would you prefer she miss her sister’s birthday and wallow at home, miserable with you instead? (Like a “good” souse should)
My apologies if my train of thought seems invasive or insensitive, just trying to help you get to a starting point, so you can address the actual problem.
Personally I don’t see the problem here. I would be happy for a loved one if they had such an opportunity, and the fact that it’s a special celebration would mean I wouldn’t even dream of asking them to decline it for me. I would encourage them to go, even if it meant feeling a bit lonely for a while during a difficult time.
Buuuut that’s just me, I’m not trying to tell you how to feel or think. Just sharing my perspective.