"He got mad and said apparently it's my job to take care of buying diapers and not his, but I said that is an unfair expectation considering it's his baby too."
The post generated hundreds of comments from Reddit users, most of them agreeing he should be contributing to the cost of the nappies and should not have asked for that money back.
"It is his baby too. He needs to help pay for the needs of the child," one Reddit user commented.
"All childcare expenses should be considered shared. It doesn't matter how separate their finances are (clearly 'completely'), there is no way for him to not be an a**hole here," another person said.
"He needs to contribute a hell of a lot more than $30 for diapers. It should be 50/50 on all living expense bills and 50/50 on all expenses related to the child you have together. And if you don't live together? Go to court and make him pay you a fair amount of child support," someone else added.