I’ve been in a serious relationship with a man for 7.5 years now. It started out great. We went places, on vacations with our kids together. Then we stopped for money reasons, but we still did all our staycations together with our kids. When vacation time came…we spent it together, whether or not we went anywhere.
BUT… two years ago, during Spring break I was surprised when he took just his daughter away for a few nights without us, because I couldn’t afford to split the cost. I felt ditched, left out, just because we couldn’t afford it. I should mention that his daughter goes away on vacation a lot with her mom. She’s become a bit of a traveler in her mature 14 years of age, so now she’s always asking him to take her places, like other countries. She doesn’t mind if we come along…she just wants to go away somewhere.
Now, this summer he wants to go away too, but I can’t afford to split the cost. So, I suggested we all go away somewhere more local and affordable. He said no and asked if I could pitch in for all of us. I said I couldn’t. So, because I can’t afford it, he’s going to just take her.
Am I just being insecure or am I getting the shaft?
LemonVibe 
That’s not the real issue, now is it? You are in a serious relationship of 7.5 years, but not married and are feeling insecure, because he’s not treating it as such. You need couples counseling.
Now, he’s only got a limited time with his daughter before she’s grown and gone and I honestly feel he should spend some of it with her before then. He’s got 3 – 4 years tops now before she’s gone. She already feels gone since she’s not with him all the time, so I honestly don’t see an issue with them taking a couple trips to themselves since YOU get him 90% of the time. Let him have those and address your real issue. Don’t use the child or these trips to address this issue. They’ll see through that as easy as I did.