She had contributed to the wedding costs.
This is the part that matters and I want to be precise about it: Daniel and I had planned a wedding that exceeded our budget, as weddings tend to do, and we had accepted contributions from both families. My mother had contributed her half. Daniel’s parents — Linda and Daniel’s father, Michael, who was a gentler person by some distance — had contributed their half. We were grateful for both contributions. We had said so, explicitly, multiple times.
What we had not said — what we had perhaps naively not considered necessary to say — was that the contributions were gifts and not investments, that there was no percentage of guest gift money owed to either family, and that the concept of our families recouping their expenditures from the envelope box at our reception was not a thing that would be happening.
We had not considered saying this because, honestly, it had not occurred to us that it needed to be said.
This was our error.