You just affirmed what I said.
There are people with bad intentions who will perform a good deed in order to manipulate others. If people really knew their intention, then nobody would bother engaging with them.
For example, men who date to see if they want a marriage tend to be manipulative and players. They are really seeking a woman who will put up with their toxic behavior patterns. Count on the marriage to be one-sided if it even reaches that level. What typically happens is a 10+ year situationship. If she doesn't break up with him first, he'll have picked her apart or use a trivial reason to discard her.