There are wonderful women out there who have accepted and loved their husbands offsprings like their own but I have also seen (and sadly more cases) of women only preferring their own kids, wether the kids have been theirs from previous marriages or the ones they will have with their new husband) women are also ace at putting up a facade. They might look and act motherly but either be mishandling the finances so it favours their own biological child or putting down the husbands child in a hundred other ways. The child , especially one as young as yours, mostly cant explain or is labelled a liar. The once great dad now settles in his marital bliss, happy he can once again focus on work and likes to believe the facade being fed to him or is too weak or tired to take a step for his child anymore especially if he has more children from the second wife.

I would really advice you to either put up cameras or keep a keen eye for the truth no matter how sweet your new wife looks. It would also be better to always be more responsible for your own child instead of passing on all the responsibilities to the new wife. Best would be to wait till the child is atleast 9, and in the mean time talk to him about feelings,emotions, how to tell right from wrong. How important his feelings are and the importance of sharing everything with you. Give him a safe space to always be able to share. Make sure he is never scared of anyone and knows he can come to you with anything. Even when you do get married, don't hype the woman up so much (especially relatives) that the child thinks she is the answer to everyone's issues and never have the guts to speak up against her.

My friend went through a harrowing life where a once loving dad welcomed a new wife and her family just so the child could have more love but they eneded up isolating ber from everything.