Great post Lilo
I think the biggest hurdle is the concept of truly understanding something you have not lived. This isn't age dependant, it is life path and circumstance dependant.
I can't understand what it is like to have a sibling or parent die, because I have not experienced it for myself. I have experienced this through friends but it has hardly the impact....they were not my
So to look at things that require special care, such as your son, it is easier for me to prioritize his welfare over my time with you because I have the experience of raising a child as well. My bond is not the same as yours because no matter how close I get, I will never have the experience of giving birth to him. He did not come out of my body..plain and simple, no theorizing what that is like or how unique the bond is I figure.
Now there are other things that I don't understand such as actually loving more than one intimate partner. In this case I have to rely on faith that you do and be respectful of your needs in this area. I support you in your other relationships and have to trust in what you tell me because I have not experienced it for myself.
People should avoid being selfish in areas especially when the needs of their partners come from places they don't understand in their.
If partners cannot work around these concepts and find ways to support each other than the relationships will probably be far less rewarding and sustainable than they could have been.