The dating world is a rough place. It's not easy to be on the same terms as someone else, and you can be going along for a while until you realize you're speaking different languages or have different expectations. To expect to be a priority in your partner's life should be the bare minimum. It's shocking how many relationships I know where one person isn't getting their needs met, and the other acts as if they're single. There's no worse feeling than seeing your partner put someone else's (nonurgent) needs before your urgent needs.
This brings us to the Reddit thread. In this story, the original poster (OP) is a woman who's in a bit of a conundrum. She just left for a week-long trip, and made an agreement with her boyfriend that he would pick her up from the airport upon her arrival. She's looking forward to seeing him, but on the day of her arrival, he informs her that he won't be able to get her. He apparently needs to help his wife's friend get home from the gym. Pretty convenient timing if you ask me.