Why do I feel guilty because my wife is giving up an opportunity that would benefit her to spend time with me on my birthday?

So here is the story, my birthday was on the 14th, we are celebrating this weekend, I found out that she has a chance to go on a trip this weekend that will benefit her career. I'm all for it, but she says she's not going she would rather spend the time with me. She said it's her choice.. I told her she should go, that my birthday is just a day, it all returns to the fact that it's her choice. Why do I still feel guilty, like she's giving something up for me?
Why do I feel guilty because my wife is giving up an opportunity that would benefit her to spend time with me on my birthday?
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