Hap(hostile aggressive parenting) please help

[Katgibbon]

Me and my ex split in March and my 3year old daughter has been having contact every Saturday since
But lately she has been behaving strange after her contact with her dad
He refuses to have her overnight because apparently he has better things to do
She has started having lots of mood swings and also very clingy and sensitive she doesn't seem very bothered about seeing her dad and seems glad to be back home
And since she can't yet talk very well I can't ask her why she is upset
I am beginning to believe that hap is a possibility
What should I do am I been unreasonable

Hostile Aggressive Parenting (HAP) is defined as : A general pattern of behaviour, manipulation, actions or decision-making of a person (usually a parent or guardian) that either directly or indirectly; 1) creates undue difficulties or interferences in the relationship of a child with another person (usually a parent or guardian) involved with the parenting and/or rearing of the child and/or, 2) promotes or maintains an unwarranted unfairness or inequality in the parenting arrangements between a child’s parents and/or guardians and/or, 3) promotes ongoing and unnecessary conflict between parents and/or guardians which adversely affects the parenting, well-being and rearing of a child.

Why do you think it is HAP rather than any other explanation? e.g. your DD struggling to cope with the transition from 2 parents at home to only periodic contact.

What makes you think this, rather than any other potential reason?