Why is he being so petty?

My boyfriend and I broke up a few months ago, after a relationship that lasted three years. It was not amicable, but we have stayed in touch and are not hostile towards each other. There have been some disagreements when it comes to our things, because we shared a lot of stuff and purchased some things together. He doesn’t respond to me when I ask about returning some of this and, when I insist, he says I have no right to ask for what he has paid for. I have also contributed in some way, but he says that doesn’t count because he paid a larger share, and also paid for a lot of dates and holidays we took together. I don’t dispute what he says but I think this is just pettiness on his part and it frustrates me because there is nothing I can do about it. Should I cut off all contact with him for this, or is it healthier to try and work it out when he is calmer?
This is a problem only you and your ex can solve because no one can do anything about pettiness. If there are no legal options available, and there probably aren’t given how hard it will be to prove who has paid for what, you can only hope that he will display a bit of maturity when he has had the time to let go of whatever resentment he is holding on to. The end of a relationship can have any kind of effect on people, from grief and anger to petty displays such as this. Cutting off all contact won’t bother you if these things don’t matter, but losing contact only makes it impossible for you to consider reopening some form of dialogue about this in the future.

How do I tell if my partner is hiding something from me?
Do you have strong reasons to suspect this? If you do, confronting someone with a direct question usually works best. Just ask for an explanation.