You Both Arrived With Attitudes Formed Long Before This

How someone feels about spending was largely settled before they ever met you.

People bring a whole history to the subject of money, and most of it was formed in the household they grew up in. Someone who watched things be tight learns to keep a reserve and feels unwell without one. Someone who watched money treated casually may find close attention to it oppressive. Someone who was never told anything may have no framework at all and finds the whole subject faintly shameful. None of these are opinions arrived at recently, and none of them respond well to being argued with.

Which is why arguments about a particular purchase so rarely resolve anything. The purchase is not the disagreement. The disagreement is between two settled dispositions about what money is for, and it will show up again next month attached to a different object. It is much easier to make progress by talking about the dispositions directly, at a time when no purchase is on the table, and with genuine curiosity rather than an attempt to correct.

Asking someone what money felt like in the house they grew up in tends to produce a more useful conversation than any amount of discussion about the current one. It usually explains behaviour that has been read as controlling or careless for years. It does not automatically resolve the difference, and it is not meant to. It moves the difference from something one person is doing wrong to something the household has to accommodate, which is a far more workable footing.