Bio child doesnt want to see stepson

[Felic23]

My partner and I have been together 5 years. His Son lives with him full time. His Son does have some anger issues (attends special school) but has improved massively and is almost fine now. The problem is the older my Son gets (10yrs) the less he want to see Ss. Hes never really wanted to spend time with him but they got along ok and made some good memories. My ss has no issue with my Son and will ask to see him. My Son said the other day totally calm not in anger that he hates him!
Im finding it very awkward as my partner wants to do stuff all of us and I dont weather to keep involving my Son when he doesnt want to spend time around his Son.
We only get to see each other with kids sometimes so would mean seeing a lot less of each other. Does anyone have any experience of this situation?

Thanks

Hi @Felic23 - the short reply is that the kids not getting along did break us up - but in truth it was more complex than that.
Even though Dp & I were divorced roughly the same length of time when we met, it became apparent as time went on that both my kids & I were further down the road of recovery from divorce than he & his kids were. I have good boundaries with my ex, am financially independent & my kids have a sm & half siblings on their dad's side - so hard as it's been we've all moved on. Someone on here said a fantastic thing over the weekend which is "divorce is not a marriage with two households" - well in dp's case it was & his ex had/has massive issues in letting him go. His marriage & divorce were very traditional - he works massive hours as is self employed, she didn't work pre or post divorce & dp was/is the sole financial provider which didn't put a strain on us but did put a massive strain on him. So, both his ex wife & kids were financially dependant on him for everything & this filtered down into everything else also. He was sole entertainer, holiday provider, school meetings attendee, lift giver, emotional prop & basically bailer outer/fixer of everything. In fairness to him he went to counselling & tried to put in healthy, respectful boundaries but the more he did this the worse & more demanding his ex became - damning me & my kids to his kids, even telling them I'd split their marriage up which was a lie of such epic proportions it's beggars belief!
So, sort of behind the scenes his kids were becoming more & more resentful of me & while they did make an effort at the start, they just stopped over time. Like your situation they were never overtly verbally rude to me or my kids, just truculent, non responsive & very excluding. I have to add that they got lots of alone time with dp but that nearly made them worse & on the holiday we went on last year they wouldn't let me get within a metre of dp (they were 13 & 16 & 19) & refused to even meet my guys half way with anything so my guys just went off and made their own friends.
They live in a different town to me & dp generally saw them in their town (where he kept a house) as they never seemed fully at home in mine (which I understood) but after the holiday from hell dp said it would be best to keep them fully apart.
Now, he was right to an extent, but I also thought he was pandering to them & was annoyed with him that he was ignoring what had gone on rather than tackle it. I got some great advice on here around that time & many people suggested that he was embarrassed by their carry on & I think he was, but he was still prepared to give in to it.
My kids aren't hard to like & I'm not saying that because they're my kids - they're outgoing & friendly but most of all they're kind, so while his kids might not have had much in common with mine I think his were just determined to not make an effort & my guys then became resentful of having to put on a game face for them.
Keeping the kids so much apart meant dp & I got eow together & maybe a night or two during the week if his work allowed & in all honesty that, combined with the fact that I really struggled with him letting his kids turn into entitled adults (don't even get me started on the financial demands) led me to end it.
For what it's worth I never expected him to force liking my kids onto his kids or for them all to spend lots of time together, but I didn't like the fact that 2 teens and a YA were being allowed dictate the atmosphere when we were all together & were also not getting pulled up on their attitude in general. Basically we parented too differently in this respect, but even putting that aside, sustaining a meaningful, developing relationship eow was difficult, as even on those weekends there would always be either an issue with his kids or he'd be in bad form over the kids & couldn't put it aside.
Sorry for the long post & for sounding negative - that's just my personal experience. Dp didn't want to break up & did suggest counselling (which we had done before) but I was done. At one point before we spilt his counsellor did say to him that we needed to do more stuff as a couple or there'd be nothing left of 'us' once all the kids left. Dp knew this but couldn't implement it because to do so would have required him to take his teens in hand & teach them a reasonable level of acceptance & independence & he either couldn't or wouldn't do that.
I think if you & your dp are always working of the same page it can work long term - but I do think differences over parenting issues are the main things that split 'blending' couples up & I think you have to be really honest with yourself about your children's 'flaws'. I think my children are wonderful but I'm the first to pull them up on/talk to them about unreasonable behaviour but dp couldn't do same. His were always fine, or more often "the hard done children of divorce" who couldn't have their dad with them 24/7. Well my guys don't have that either but they have survived!
I really hope it works out for you.