It makes my heart very heavy. Hardly a post on this forum without someone jumping in with an overwhelming assumption of bad faith.
If you do this to new posters here - how would you like to be in their shoes? People complain about Disney Dads, but the Disney creed infects more than Dads. The whole 'whatever a stepmum does is automatically from the worst possible motives' is utterly rife.
People are people. A whole mix of reasons for much of what they do. Most start out with the best of intentions and try not to do evil. Don't force people into your narrative - they are writing their own stories.