Son doesn't like my partner

[Tulip55]

Have been with my partner for 2 years now, he stays over at mine half the week. My daughter seems OK with him and gets along with his daughter. My son is deeply unhappy with the situation. He feels left out when the daughter stays over and can't stand my partner.
We had some teething problems at the beginning, my partner told my kids off a few times, not harshly or loud, just stop doing that... but my son took it badly. I saw it as no different to if my son was at a friends house and did something wrong, I would expect their parent to tell him. My ex told my son it's not OK, so he felt justified and things have been bad ever since.
I discussed with my partner and he leaves all the disapline to me now and has for some time but the situation isn't improving. I'm worried it never will.
I'm trying to keep the right balance between keeping my kids happy whilst not letting them rule my life.
Anyone in a similar situation or has been? Really need some support. I dont want to ruin my relationship with my son, but I dont want to end this relationship with a man who treats me so well and does all he can for me and the kids because of some small mistakes in the beginning. We are both learning at this blended family thing as we go and I feel like my son is being unforgiving over small things that happened months ago.

I strongly suggest you take a step back the relationship for the sake of your son and your relationship with him. Spend time with your OH separately, away from your DS, and don't force him to be in a situation he isn't comfortable in.
I have a step Parent that I didn't particularly get along with while growing up. As you put it, there were a few hiccups at the start of my DFs relationship with his now wife. She crossed the line a few times while attempting to parent me and my sibling, which caused a lot of friction between us and my SM and also her DC.
Thankfully, we didn't live with my DF and would only see him a few weekends of the year and half the school holidays. Which meant we had the choice whether or not we wanted to spend time with him and his wife. But whenever we did spend time with my DF, his wife would always be included during our time with our DF, and this did negatively affect our relationship with our DF.
I get along ok with my Stepm now, but the damage is done, and we have an amicable relationship rather than a positive one. My relationship with my DF is also better now, but, we probably aren't as close as we could potentially be due to his decision to force us to play happy families with his wife when there were clearly tension between us.

Not personal to me at all - I’m lucky with my set up. But I am disgusted by women behaving like this to other women.

Apologies, I may have misunderstood your post.