The good cop / bad cop scenerio is very common among divorced families. A lot of times, the parent who doesn't have full custodial rights will attempt to drive a wedge between the divorced spouse and the child by being very lenient and showering the child with gifts, affection, etc.

This is a common issue, not just with parents of children with autism, but families of neurotypical as well.

An divorce expert can probably help you with this matter as well.