My answer is a resounding NO!
Here is why.
Right of association is established in the Constitution. It assumes no liability or responsibility for the mere act of associating with, or NOT associating with another citizen.
If the mother of the child was concerned in the least, then she might have either pressed for marriage, or left the relationship earlier to protect the emotional needs of her child.
There are no laws (except in the states that I mentioned) the require someone who is generous at one point, to be obligated to continue such generosity over the fact of a child becoming accustomed to such largess.
The states that have instituted laws forcing step-parents or boyfriends to support children that are not their own, are acting in a purely un-constitution manner; allowed only because those states have activist judges who don’t care what the constitution says.
The first responsibility of a parent should be to protect their child, so I blame any mother who allows her child to become emotionally attached to someone who is not committed to both mother and child.
I have advised all men to stay away from single mothers for this very reason. Not that single mothers are all bad, but because in certain states, a man can be held responsible for children not his own, merely for associating with her and her children for an extended amount of time.
Women with children need to establish a man’s intentions early on in a relationship, in order to protect their children. If a man isn’t marriage or father material, then what happens next is HER responsibility. If she decides to carry on with a relationship with a man who won’t marry her, then whatever happens after that is her problem, not his.
The fact of a man having a lot of money does not justify him being forced to share it with others. Emotions don’t belong in the law.