this is an upsetting (can’t think of the right word) situation that must clearly happen for many NRPs once the dcs are teenagers that I’ll bet they don’t even think about (no judgement, I don’t think I would think that far either) when the decision is made to split, then to go EOW, move, start new families etc. their relationship with their first dc just disappears unless they put in all the effort.
100%, except I don't necessarily agree with the last bit about the relationship disappearing.
I think it's a really hard time for the NRP, I know it will be hard on my DH, because I guess they just feel like they will always see their child on some kind of rotation basis and, as you say, they don't necessarily think about what life will look like as the child grows older.
But I just think it's the natural way of things, it's just the nature of a child growing up, it's just the RP will likely get a couple more years of the child living under their roof, even if they're out all day and evening and just passing as ships in the night. Then the child will move out of the RP's home and both parents will be in the same situation...things change a lot but then both parties likely start putting in a little more effort to arrange times and dates etc.
I think it's easy to judge as a resident parent - not aiming this at you at all arethereanyleftatall, just in general - because an RP will still get those small daily interactions, even if they are not actually spending a great deal of time with the child either - they will still know vaguely what's going on in their life, even just by their comings and goings. They don't necessarily think about how much time they are actually arranging to spend with their older teen vs the quick chats over breakfast or whatever, but then they think the other parent is remiss for not managing to schedule dates with the now super-busy and social teen, especially if said teen is also in education and potentially working a PT job on top of that so doesn't have a lot of free time to begin with.
I honestly think it's just a natural progression which hits all parents eventually, it just hits NRPs first because they are already in a position of having to book time in.