This is completely academic now, because I have left my ex, but there was an issue which always caused rows and I still ponder on whether I was justified.
Ex had three grown sons - the youngest already 18 when I met him. We lived abroad, so we got into the routine of all three coming to stay for a week or so in the summer, sometimes with girlfriends as well. This was always good fun but obviously entailed a lot of extra work for me and a massive extra cost.
We ran a business together and for the first few years we were doing well, the DSSs were still studying, etc, and the expense of these visits were never an issue to me. However, latterly we were VERY short of money, DSSs were all grown men with excellent jobs and I began to feel that they should be expected to chip in for groceries, petrol, etc, and not simply expect us to fund an all-in holiday for them all every year.
It didn't help that our own DS's birthday is at the same time and I was always struggling to afford his presents (always modest anyway) and party. The cost of the three to six extra people meant we would spend in a week what would normally do for a month.
Whenever I tried to broach this with ex (who never shopped or took any responsibility for finances), he would just fly into a rage and accuse me of "hating" his sons or trying to stop him seeing them. To me, it is simply common good manners to offer a contribution if you stay in someone else's home ... even a small token gift or the offer to take us out for a meal would have shown some appreciation.
Odd that this one small problem in a relationship fraught with huge problems should continue to niggle me, but I'd love to have some independent views on it.