Just want to know if this is weird or is this normal for a close brother and sister relationship. Me and DP have been together for a long time and have always included his sister in events, holidays etc. We recently went on holiday together and whilst there she kept sharing food ofd the same plate with him (e.g. biting something and saying do you want to taste amd giving the rest to him) making sure he has drinks, buying things from the shop for him, sharing ice cream together - I feel bad as I am his DP and should be doing all this for him but she is quick to jump to his needs. I do all this for him when we at home and he does things for me. I ask to share food with my DP on holiday as I don't eat much but he just blanks me. And on the recent holiday they were sitting together all the time and doing activities together so felt like I was third wheeling! I have a sibling and I will do anything for them but not to this length as we are complete opposite in what we like. I did ask him about this and told him how it makes me feel bad but he just said it is what it is.
Is it me or is this normal?