Co-parenting is rarely an easy thing. As a relatively reasonable person, you keep thinking that this thing has to get better. But it doesn’t. If you notice that the other parent is self absorbed, he/she may be a narcissist. I always have had the notion that the word narcissist was overused, but really, it describes that parent who is tuned in only to what is best for themselves, not the child. The parent lacks empathy for the child’s feelings, wants and desires. It is possible to navigate co-parenting with this individual, but it may make you want to throw your hands up and just say no. The upside to that approach is that you may not have to deal with that parent for a short time; the downside is that that parent may seek to hold you in contempt if you violate a parenting plan or even seek to modify the parenting plan to reduce your time with the child.
I would encourage you to read more about this topic in Karyl McBride’s new book “Will I Ever be Free of You? How to Navigate a High-Conflict Divorce from a Narcissist, and Heal Your Family” (Atria Books, a division of Simon and Schuster).
See https://divorcedmoms.com/articles/how-to-coparent-with-a-narcissist