switch a day with X to make up, and put her on notice that next time she doesnt ask before buying the answer will be no?

I would be reluctant to disappoint D15 this time to make a point with X.

Adinva 51, S20, S18
M24 total
6/15/11-12/1/12 From IDLY to H moving out
9/15/15-3/7/17 From negotiating SA to final D at age 50
5/8/17-now: New relationship with an old friend
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Happiness is a warm puppy.