I see enough posts on this forum advocating "can't the child have a random illness" when the mother doesnt want the father to have access for what ever reason.
We have friends who have had their lives made extremely difficult regarding access. One in particular, well the mother should have been sectioned, really she should have been removed from society in general, you wouldn't let her loose with a goldfish let alone a child. Long periods of restricting access, demanding more money from the father to allow access that weekend, phantom illnesses, sports events, her family events, outright refusal.
Then she would go the other way, what can only be described as dumping the child back with the father when she had a new BF - really it was all mind games on her part and this shit would all rear it's head if he ever was trying to establish a relationship.
I remember one time when she 'dumped' the child for a fortnight so she could go on holiday with her new beauknowing the father had to work, had no childcare so I ended up with him for 2 weeks.
Then she changed the childs name
, then instructed the child to call each new BF 'daddy' didn't matter how long they were sticking around.
So you see some women (and men too) make life very awkward for the NRP to maintain anything like a relationship, out of sheer bloody mindedness.
I'll give our friend his due: he stuck around, through what is now 16 years of her shit, never able to sustain another relationship because that woman would ensure she sabotaged every relationship he tried to build.
So, Op unless you are in possession of all the facts, it's best not to judge.