Sorry if this isn't the right place to ask. I just really needed someone's opinion. I (25f) recently started seeing this girl (25f). Before we went on the first date, she disclosed that she was ENM. I told her I appreciated the communication, and that while I didn't know much about it, I was open to still getting to know her. We went on several fantastic dates, but at a certain point I realized I should probably find out more about what ENM means to her. It wasn't until this point that I learned she has a long term boyfriend and is just looking for fun dates on the side. While I recognize that she disclosed not being monogamous... I still feel like she should have also mentioned having a primary partner. Am I wrong for being a bit upset about how this was communicated to me? I was under the impression that she wanted a relationship, just that it had to be an open one. I wasn't expecting to be walking into an already existing open relationship.