DP and I only been together 2 years ish. Our DC so far get on pretty well (we meet up all together maybe once a fortnight, sometimes more sometimes less) but see each others DC on our own more frequently, say 1-3 times per week. I thought I was making super progress with DP's eldest (13) especially, as she's quite affectionate and relaxed with me now. She'll curl up on the sofa and is cheeky in a funny nice way with me. I've always been careful not to parent in any way, give them time alone with their dad so as not to infringe etc. and followed their lead with me. I get her the occasional treat and my main aim is just to be daddy's girlfriend who is nice to me type thing. So so far all been great. 'DSD' (for ease of typing) is prone to occasional sulkiness but I seems pretty typical teenage behaviour (and my slightly younger DD can be sulky too so I get it). She's a sensitive soul, really genuinely lovely kid. Recently DSD and my DD kind of had a falling out, not an argument as such but DSD got annoyed by something my DD did. DD didn't actually do anything, she didn't want to join in on something that was important to DSD, which in fairness to DD would have caused her stress, plus she's a bit younger so couldn't articulate it very well. In absolute fairness to DSD, she tried to make the task more inclusive, but was still a no from DD, which meant DSD couldn't do the thing she wanted to do. Cue tears all round. My DD is really cut up about it (she wanted to join in but got stressed and shut down) and DSD is pretty angry. But now DSD is being REALLY frosty with me. I've only seen her once very briefly since the incident and she just glared at me, pretty much stormed off, and is still really furious about the DD not joining in thing. Im at a loss. What can I do to fix this? Or should I just do nothing and let it blow over? Should I carry on as normal or back off for a while? I'm dreading the next group meetup with the DC too, so I think I'll delay that for a while. I can deal with my DD no problem, and she wasn't really in the wrong so I know I'll be able to work through it and she'll be okay, but DSD is still an unknown quantity to me, if that makes any sense? I'm so not equipped to deal with this. I'm probably being completely over dramatic about it and I know seasoned step parents would probably laugh at the triviality of it compered to further down the line stuff, but I'm feeling quite down about it as it caught me so off guard, I didn't even consider that it would be an issue. I'm such a super low conflict type personality and quite sensitive to personal relationship problems, and my DD is exactly the same. I just don't know how to fix it. I'm giving it too much thought aren't I?! Any advice would be welcome right now!