I have to say that my OH has had a very difficult battle with the legal system in relation to his DD.
She is now 17 and is a gorgeous clever young lady but her life has been made much harder than it needed to be by a system that saw a mother as the primary carer and the father as a financial provider.
My DH has never earnt much money but when I first met him he was paying 2/3 of his salary to his ex, looking after his daughter most of the time and still buying most of the big purchases for her such as school shoes, coats etc. She lived in the 'family home' and he lived in a room in a shared house ( with many unsavoury people and so never went out of the room!).
So my DSD spent over half her time living in that horrible environment so that the rest of the time was in a nice house... Her mother has mental health issues and over the years drug and alcohol issues. When she was/ is with her dad it was as if she didn't exist and she would never contact her even if she was ill etc. DH was always DSD's main carer and even after he moved out was always the one to look after her if she was sick, sort out school things, uniform etc etc..
however, ex has always 'needed' DSD to be her companion when she has no friends or wants her to accompany her on her latest thing (always a fad going on that DSD has to join in with and usually pay for herself!). So DH has never been able to decide/ negotiate when DSD was/ is with him... This has always been dictated by ex... Often changing at very short notice and often used in anger if she felt he was slighting her in any way.
He left the relationship because of her violence verbally and physically, but has never left his daughter, always put her first ( before me which I agree with, this has changed a little since we've had two more kids, she is now one of three and so sometimes isn't first but I think this has been a good thing for her, she loves her siblings with all her heart and they are incredibly close)
About 8 yrs ago things were terrible and she was always threatening to take her away, denying access and generally messing with DSD's little mind and so my DH went to court for a residence order. Long story but it was hideous, abusive and made things 1000 worse at the time..she got a residency order and they wouldn't make a contact order saying that they would only do that if they couldn't agree after another year ( they wouldn't have been in court if they could agree!)
After that we did cut the maintenance payments as we realised the money never went anywhere near DSD and we used the money to buy things directly for her.
My OH was so hurt by the court experience and she made so much of being the resident parent... But on the other hand DSD knows that her daddy did/would do anything for her and that was very important and I think helped her psychologically.
Sorry this had been so long but wanted to show that there are mothers that puposefully cut maintenance and do act spitefully just as there are flakey fathers... All situations are different and unless you are part of it you really don't know.