It is true that when a court makes and arrangement for contact that if either parent doesn't keep that arrangement it reflects very negatively on them and restricts the next arrangement.
My XP was emotionally, psychologically, financially and sexually abusive to me. My DD was the result of him raping me. He cheated and drank and alienated me from everyone. He told lies about me to family and friends, stole from my family and blamed it on me. He was completely uninterested in my DS and told me he wanted nothing to do with him as he was boring.
He left to be with his current girlfriend. He had told her that he and I were just living together for the sake of DS and so didn't want to admit to DD being his - also didn't want to admit the circumstances of her conception.
He stopped seeing DS, told everyone I had prevented access so was pecked by his family into taking me to court (for access to DS but not DD). He harrassed me and was warned by the police, he got his family and friends to harrass me in the street and his g/f to pretend to run me over when pushing ds in the pram then drove off laughing.
He was horrible. He was also being investigated by the police because he was suspected of having sex with an underage girl and having child porn on his PC.
We went through court and eventually ended up in mediation (he wouldn't go to mediationa s couldn't face me). The court system was very fair. Things were set up to protect my DCs as I requested and he was forced to have a dna test for DD and to apply for access to her too. He was unreliable with every arrangement the court made (they try several to give them a chance) and eventually the case ended with the magistrate telling him there was no evidence that I had ever been obstructive to him having contact and that his behaviour was completely out of order and he needed to apologise. The case was discharged without a contact arrangement on the basis that I was in control and not being obstructive.
After court he was unreliable with our arrangement and this time DCs did start struggling with the let down so I insisted we had to go to mediation before I would make another one.
In mediation we agreed (finally) that he didn't want to be a father and so he now has very informal and irregular contact with the DCs in a similar way to a grandparent. I have open communication with the DCs about how he loves them and is a lot of fun but can't manage to look after them and that is why they don't see him very often and they know this is true because they experienced him trying and failing to be a father. I respect him for admitting he can't be a father. He has a good relationship with the DCs because everything is honest. DS is now 4 and DD is nearly 3. Making the link between their father and their granny was helpful for them as they know granny loves them, they also know she doesn't really want to look after them all the time and they know they don't need to expect to see her regularly but that when they do it's a lot of fun.