My XH was far more distant than my DH ever has been, and my XH and I had no children.

It has less to do with kids and more to do with the personality of the spouse, and their ability to put their spouse first.

This was definitely true for me when my SDs were coming EOW.   I didn't agree with a lot of my DH's parenting choices, especially the Disney Dad aspects, I felt he chose them over me, and took their side when he should have remained neutral, or at least tried to see my point of view. These things, over the years, caused anger and resentment for me.  We'd go long spells when I felt quite distant from him, both physically and emotionally.  

Now that the EOWs don't happen any longer, this isn't an issue any more. 

My biggest problem with my DH is that he acts differently when SSs are around. We only have them EOWE, so maybe it's more noticeable because most of the time . When SSs are around, he's likely to feel more stressed, more likely to snap at me, more likely to decide things on his own without consulting me, and completely unreliable (i.e. if he's told me he'll do something, he often will "forget" when SSs are around). It does drive a wedge between us, because I feel less than his wife when his kids are around. Part of it is him falling into old habits, part of it is that SSs are sort of difficult right now and he finds that stressful (and when he's stressed, his initial reaction is to tune everything out).

DH will also periodically say to me that he feels like he has to make sure everyone has equal attention when his kids are around and I tell him that I'm not on an equal playing field with his kids. I'm his wife, therefore, if I need something from him or he's promised me he will do something that has to be done while his kids are around, he can't leave me hanging, that needs to come first. I'm not suggesting that he ignore his kids and only spend time with me, but if I need him to do something that I can reasonably expect my husband to do, then I expect him to do that for me, even if his kids are around. 

Absolutely feel this way! He tends to forget he has a “partner” in our family. The kids treat me like I’m not here & I feel like my kids & I shouldn’t be here when they are. It’s very, very hard.

It seems to be a common theme

I've never fully understood it myself, but it does seem to be the norm unfortunately

It does get better when they get older, at least in my case it did

We recently spent a few days out west with YSD, SSIL and SGD and DH was great to me the entire time, none of the old exclusion tactics and treating me like I'm invisible

It  did take many years of constant discussion over it, taking off and doin things on my own when SD was around, and not letting unacceptable treatment from DH or SD slip

I feel for you, it can be so frustrating!

Not an unusual feeling in blended family marriages.  It is unnatural for there to be a near constant source of interference in a marriage.  Sadly, far more often than not, that is what Skid's are at a primary level.  This is exacerbated by the breeder parent who brought the prior relationship spawn to the new marriage making those kids their priority rather than making the marriage and their spouse their sole sole top priority.

My perspective is that kids, regardless of biology, never take priority over the marriage or the partners in that marriage. Ever. PERIOD!

Being equity life partners also makes the spouses equity parents to any children in the home regardless of kid biology. 

When your DH pulls this shit he is failing to step up and actually be your equity life partner.  It is time to start a dedicated campaign to drive clarity into your DH's skull and nip this shit in the bud.  He needs to force the integration of SD into YOUR joint family and not separate himself and her from that family.  You should have zero tolerance for his crap and for the SD's crap and force integration.

It isn't fair to you or your children for your DH to have started or to continue to perpetrate this travesty on your family.

Since you don't provide a whole lot of detail I don't have any comprehensive ideas of how to accomplish this but you definitely need to do something.

Take care of you and your kids.

And it does dampen the intimacy and make it feel more of a chore shen it should be a connection

i’m angry when there is urgent stuff like kids getting vaccinated and hubby is forever busy with work and sport events for work and not free then his kids with ex suggest a meet up that or following weekend and instantly free. Meanwhile our toddlers getting vaccinated totally forgotten about

i feel i am constantly reminding hubbynhis priorities aren’t in the right place and when he pulls this shit i feel he totally negates me as his wife and treats me like nothing and thats not the way you should treat your wife

in my case forced integration i don’t believe hubby will enforce, he doesn’t want the drama and i have warned him with that mentality that will be the cause of me leaving him