No, I wasn't being selfish. I honestly understood why she did it.
Also, she did tell me that one of the reasons she left for a month was she confessed for the first time in her life to someone that she liked very much (an INTP) and that he rejected her and then stopped answering her and they haven't talked since. That, along with all the other things, is why she disappeared for a month. We weren't as close/intimate then, and our intimacy obviously grew a lot after that, and it didn't bother me, because we weren't/arent exclusive. Now if she was telling me she loved me and stuff like that, then yeah, I would have a major major issue with that happening, but at the time? No.