Struggling with stepchildren relationship

[OliveTiger]

Hi,
My partner and I have an 8 month old baby and I am step parent to 2 older children. My SC and I have never had an amazong relationship because they absolutely dote on my partner and rightly so but this lack of needing me along with a lack of natural maternal instinct towards them has meant that our relationship is adequate but doesn't thrive. Since our new arrival I have become more bothered about their behaviour, they are just being kids but I feel my partners guilt for only seeing the children half the time allows certain behaviours to not be addressed. My partner and I are now at breaking point as I am struggling to be as warm to the SC as they would like. I am super maternal with my own but cannot settle into a caring step parent role, it isn't that I dislike them. Yes I find them annoying at times but I think it is fear of rejection and a frustration at my partners unfounded guilt, they are a great parent and a lack of knowing how to be warmer at an appropriate pace that isn't awkward yet fast enough for my partner to see a rapid change is going to break us up and I am terrified.
Sorry to ramble but how do I become more warm and less irritated, do I just fake it until it becomes more natural?

I would say yes, fake it.
I'm not a stepmother but even with my own children when they were being particularly defiant or constantly fighting with each other I had to fake an understanding and love I did not feel. I was a sahm much of the time.
But some counselling to discuss DH's guilt and your lack of warmth would be useful I think. So you can both see things from the other's point of view

It’s difficult.

I am not a fan of being around others peoples children, for prolonged periods so I get where you are coming from.

I have seen it on mn, a lot, where once the step mum has her own baby their attitudes towards the step kids changes and they struggle with the relationships. I think it it’s quite common.

I think you can only resolve this by working with your partner. You say they shouldn’t feel guilty. But they do. And it’s understandable. But the next step is to work out whether they are letting poor behaviour slide or you are being a bit over zealous in your opinion of how they handle it. And talk it through with your partner.

And for you, you need to work on realising they are children who didn’t ask to be in this situation and they need the adults in the situation to understand that and not blame the children for the other adults decisions.

Unfounded guilt. They should feel guilty about seeing one set of children half the time and another set all the time. If you don't like being a stepmother - divorce him and make better decisions in the future.

This is all standard in second family situations. Unlikely you’ll have much maternal instinct towards the steps especially now you have your own. He will do the Disney dad thing because he feels guilty and there’s always the possibility they could turn round and say we’re not coming to stay any more. It’s likely to be an incredibly bumpy ride which is why it’s usually a poor life choice for women to have a baby with a man who already has children. Now that you’re here though all you can do is try to empathise with the kids and try to work with your partner on how he manages their behaviour. With the maternal stuff yes you have to fake it.

I think this is why blended families don't work, it never is in the children's best interest.