Often, when parents are separating, the child tries to either play one against the other or select one and disdain the other.
A wise parent refuses to be played, and when it comes to selection, realises this is a ‘competition’ the child is attempting.
In the ‘competition’ the parents are to strive to give more and bigger and better than the other.
Parents who realise this, step back. If they have an amicable relationship they can decide who does what.
Parents who don’t realise this will be used, abused, and drained.