These issues all of us deal with related to step/blended/whatever you call them families are so complex!
I've posted many times about my FH's guilt parenting, this notion of child-centeredness that means SS has always gotten all the attention he wants, been the total focus, gotten whatever experiences/lessons/vacations/etc. he wants from FH...without giving back anything, being responsible for anything, etc. He is 10.5 and doesn't really even know how to pour himself a bowl of cereal and lies in bed on the weekends until FH makes him breakfast and calls him to come eat it.

My schedule/life with FH is complicated. I work 3 hours away and so am gone from either late Sun PM/early Mon AM through Thurs morning.
FH always has SS on M/T, along with alternating weekends. This, I figured, would give them continued QT (our engagement is new), while easing into blended family life.

I've posted a great deal and replied to posts about my FH and his relationship with SS10 (his bio son)- whom he's described as "his peer." Always treated him like his partner, taken him to adult parties, SS assumes he should be a part of every conversation, etc. This, combined with the fact that SS has no responsibilities, doesn't even know how to pour a bowl of his cereal, doesn't even carry his backpack from the car- and is emotionally immature- have made for some stress since I moved in with them when we got engaged last fall.

To have "connection" w. SS why does FH have to disconnect from me?
I have realized that the stress I feel, the isolation, anxiety, and lonliness that are at times so overwhelming- this is b.c FH can't assert his connection to me or be a "we" with me when his son is with us. I wish he understood this. That I can't have that w. him only when SS isn't w. us. I need it with him and from him all the time. And when he takes it away b.c he thinks he can't be connected to us both I feel so sad, so alone, panicked, and then angry.