Hi ladies,
Hoping you can offer some advice as I’m struggling and starting to feel a little sad. Before I continue I wanted to say I have read in to this and know it can take a good few years.
I have two sons, separated from their dad over two years ago on excellent terms (we’re good friends and the boys regularly see us together) and started seeing my partner 15 months ago. We left it a good while to do introductions and my partner was introduced initially as my friend.
We’re 7 months in to this now and my oldest son (5) is extremely resistant. His behaviour when my partner is around is a complete contrast to his true lovely personality. He talks about awful things, death, violence, gore. Things he would never say otherwise and I’ve no idea where it comes from. He becomes loud and aggressive, goading my partner as if wanting an argument. He behaves like a grown man who doesn’t want another man in his environment, maybe exactly what’s going on I guess?
My partner tries changing the subject and distracting him, we’ve also tried ignoring the behaviour all together and nothing seems to work, it just serves to escalate the situation until we’re in a full meltdown where he screams, hits things, throws things. I’m sure you’re familiar with the tantrum 
Any tips and advice from anyone who’s been in this situation would really be great. TIA X