It seems a bit odd since you're all in the same state and the skids live with you.  It would seem less surprising if none of the kids lived with you and they were scattered.  Have your kids come to visit and his just haven't been home at the time?  I guess it's not a priority for some or all of the children or it would have happened.

I am not certain so much odd, but it may be that you and your SO may be on different pages.  Part of that may be that his kids are younger, and he is more in a parenting mode.  Have you two spoken aout marriage?   

I could be jumping ahead but you mentioned you do live with them now and you are getting another house and moving in the Spring...

It sounds like your relationship is moving forward and I am not sure if you are getting married? Buying the house together? But it might be something you might want to do before you move forward.  Not that you wouldn't continue your plans whether or not everyone gets along but it might help with a future blended family if your kids were more part of the picture.  

It sounds like his kids are part of things because they live there.  How do your kids feel about the situation?  Have they met your SO and just not his kids?  I am curious, how do you celebrate holidays?  Is it separately since the kids have not met?  

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Either he is not truly interested in blending lives and is just enjoying spending time with you with no real thought as to permancy OR he is hiding something about his children that he would prefer you don't know until you are locked down by marriage or a joint property purchase.  Obviously there have been holidays and family events like birthdays but none of them have been celebrated together?  Even though there are grandchildren?  No.  Something is off and you need to know what it is before you get in any deeper.

I speak from experience.  I stupidly fell for the crap about trying to keep things peaceful with BM and the skids not being ready to meet me.  He even trotted out advice from their therapist that it was more likely that we would have a good relationship if we let them "come to me."  It turned out that they were the most spoiled, snotty, materialistic pre-teens and teens outside of reality tv and even their own grandparents could not spend long periods of time with them.  They also had been completely convinced by BM that I had broken up the marriage and their hatred of me was extreme.  He knew very well that if I met them before I was good and nailed down I would bolt like a frightened rabbit.  He admitted it about 2 years ago while we were talking about how much things have improved with the skids over the past 10 years and how hard it had been for me at times.  He was shocked at the depth of my fury on finding that out.  Don't make the mistake that I did.  

It IS weird they have never met. But then again so many combined families end up cutting ties because of major drama. One side is nice the other side are aholes. Hence cutting ties completely.

So, I agree with CG above..........enjoy your peace and live life fully, drama free. It is great!!!!

Not only are your kids older, they are also in a far different phase of their lives than DH's BKs.  So a meet would seem to be mostly for  your benefit in righting what seems odd ot  you.  There is absolutely nothing wrong with that.

Is there a compelling reason why  your DH would want to avoid that introduction?  If his kids are reprehensible he may not want to have that come out to your kids.

I wondered for a long time why I wasn't meeting my husband's daughter. When we were engaged, I pushed it, worried she might be an issue in the marriage. We made several plans to get dinner. SD cancelled them all at the last minute. I kept asking my husband if there was a problem. He assured me she was happy for our upcoming wedding and just "really busy."

Flash forward a decade. I haven't seen her in two years and she's been an issue (the ONLY issue) in this marriage. I see clearly now that back then, SD may have been telling him, "Yes, Daddy, I'm sooooo happy for you!" but by repeatedly cancelling, she was telling me, "No, bitch! I will never accept you!" And she never did.

You really don't know what his kids are telling him. Maybe they aren't saying it, but your partner knows it wouldn't go well if everyone met. You don't know why there hasn't been a big happy family dinner. But if your relationship works now, I'd leave it alone.

I wish I had never met my SD.

Be grateful that your kids have lives of their own and are not living in your basement.  Plenty of stories here of grown skids older than yours moving back home with their own children in tow. My kids and DH's kids have met but that's where it ends. Neither side goes out of the way for a continued relationship, they all live their lives and the show goes on.  If they meet then great, but for both sides it likely won't be a life changing event. Your kids have kids/jobs/lives and probably don't really care to incorporate older step siblings into their lives. His kids are teen and young adult and are all about themselves and their phones.  

I do not have children.  But I have a sister who was born when I was almost an adult.  Our mother died young.  My sister has never married, and we are very, very close.  No I am not her mother, but I'm the closest thing she has to a mother.

DH and I have been together for about a decade.  DH, my sister, and  DH's son (SS34) all live in the same town.  For most of that time we all lived within 2 miles of each other.

My family is very open to having extras for holiday celebrations.  When DH and I were first dating I invited SS to come to a holiday dinner at my aunt's home.  The night before SS came over for dinner.  OMG he was high as a kite and looked like hammered sh*t.  One of my cousins is a DEA agent.  No way I could take that disgusting worthless POS to a family event.

My sister has never met SS.  She probably never will.  Why would I want my sister to meet someone like that?

My husband and I have been together five years and our adult children haven’t all met.  His son was in the Navy and deployed the first two years and my son is active Air Force stationed in Utah and we love in Texas.  Two kids in Oklahoma and one 2 hours south in Texas.  We’ve had three together in one room ONE time.   His are extremely jealous of mine and I don’t see them ever having a relationship.