Absolutely agree with pretty and banana. DSD lives with us but sees her mum every weekday. Therefore it's a normal and close mum DD relationship. There's no parental toxicity and DSD's mum and I also get on. Perhaps for those reasons DSD and I have often gotten close. We've had many 'firsts' related to clothing, grooming, make-up, boy talk, food, travel etc., therefore I understand that inner excitement as you share and treasure certain moments.
But right now she's distant with me, her mum and her dad (probably in that order and perhaps understandably, especially as Year 11 teen). I trust that everything will be OK, we're all appropriately active and involved. It's not DSD's job make me happy or my right to make her a parenting project of mine. My role is to help (in agreement with her dad) guide and teach her in as loving a way as possible. Paradoxically, healthy disengagement enables that as you protect your own heart and pick your emotional battles. Whilst this is important now, it would probably be even more vital if we had parental fall out in our case.
I remember reading that blended families is an unhelpful term - assuming enforced harmony - because of the inequality of bonds, affection and authority, which can make for an unpleasant taste. But thinking of step families as slow cookers suggests that in a delicious stew, for example, each ingredient softens at its own pace, over time, with its own special contribution to the meal. But... although it's still a delicious stew, the ingredients (being individual and unblended) can harden again too! Silly little analogy, but I've found it helpful and true. Perhaps true for most families actually (certainly friends of mine in intact families also attest that they face similar incidents and emotional challenges, whether because of the other parent, siblings, grandparents etc).
I reckon if we focus on what influence and authority we have in our adult relationships, and play the long game, we'll have done our best for the children we (step) parent as you and cali have said.
Sorry - I do get a bit long winded and philosophical
. A direct question: apart from saying some conflicted things to your son, what else has happened that makes you think it's about her mum disliking you? You mentioned it's hard when you comfort her or do her hair. Have you been asked not to do this then? Children are influenced by school / internet too, not just their parents. Not underestimating what's going on for you, I just didn't see from what you said what the mum's actually done. Is anything going on in the other home?