I've learnt that by going for a 'younger woman' or 'having a baby' or 'moving in', is not because they care. It's far from it.
It's all to do with manipulation and, 'ownership' and having a place to live with someone who will serve their needs. End of!
A narcissist may feel that a younger woman may be more easy to manipulate and by having a baby the woman is now more trapped into the abusive relationship as there's now a child involved and it will be more difficult for her to leave.
She was most likely 'love bombed' and had no idea what was coming. Plus narcissists like to 'move fast' so even if she had her 'doubts' or saw a few red flags, she most likely brushed them aside because on the whole at the start of a relationship narcissists come across as good people right!? and we reason that people can't be perfect can they?
Narcissists think they own their partners and feel that they have the right to tell them what to do. We've all experienced it.
The child in the relationship will simply be used against the non narcissistic parent as a pawn.
Anything the victim does in the relationship will be stored up in the mind of the narcissist, and used against the victim. This is why we can't trust a narcissist, or tell a narcissist anything, they will always use what we say or do against us. We know how they will twist the truth, and shout over us when we try to correct them or defend ourselves.
They try to get us to conform to their own version of reality.
We often hear of narcissistic parents using children against their partners, by threatening to take the children away, or threatening to tell authorities the partner is an unfit parent etc.
This is to keep the victim in the relationship so the narcissist can continue the abuse.
From the outside it may look like the narcissist has settled down and is treating someone else better, but nothing could be further from the truth.
The new partner may be suffering even worse now that a child is involved.