It's hard to have feelings for a child then see them turn away.  We want to know them, to guide them, to have a relationship because they are part of our DH but then they're gone.  I would try to grieve your hopes and concentrate your efforts on your DH and bios.  Your SD will always be a part of your life but on the periphery.  I'd try to maintain a polite and civil relationship but not hope for much from her at this point.

Whenever I read about a SK drifting away, I feel a tinge of guilt because I did this with my dad who adopted me when my own dad died in WW2.  I got married, had 2 kids and never gave him a thought til I had to move back with my folks during my divorce.  He was wonderfully supportive and I had matured, too.  In later years, we still werent touchy-feely close but we went out to eat every Fathers Day and he confided some of his fears when he was terminally ill.

You all are years away from all this but my take on it is that it's frequent for SKs to pull away. Its normal for teens to be greedy for gifts.  It's not unexpected for teens to make insincere thanks ("miss you").  Take the long view -She will be a part of your life as long as you are with DH and she will always be a part of your DH and children's life.  Disengage for now but keep the door open for the future.  Good luck.

I think in some step situations being just the girlfriend is seen as tolerable, but once there's a wedding, it's seen as a betrayal. In hindsight my DH'S elder daughter (who was thirteen when we married) started distancing from her dad after the wedding. At the time I chalked it up to normal adolescent behavior, but I think on a subconscious level if she couldn't be Number One, she just wasn't interested in being around her dad.

Clearly something isn't right between your H and his daughter, and after six months he's letting the tail wag the dog. If he doesn't take action to resolve this impasse, he may lose his daughter entirely. Some father - daughter counseling is my suggestion.

Your SD sounds very similar to my SD11. Custody is currently 50/50, but we would not be surprised if SD asks to go live with BM. She never wants to stay her full visit here. SD was here for Christmas evening and the day after. We did gifts both days with DHs side of the family and also mine. Literally as soon s family left, SD asked DH if he could take her to BMs. He said no and explained that she needs to spend her scheduled time with us on the holidays.Well she didn't like that answer and went in her room and pouted the rest of the evening and refused to spend anytime with the family. 

Well the next morning at 8AM DH got a text from BM. "On the way now." DH had no idea what she was talking about. Apparently the night before SD was calling and texting BM begging her to be picked up. DH was just done at this point. He had explained to SD the importance of spending time together and then she goes to BMs anyway. BM apologized and said she should have checked first. DH then basically said, "if you want to go, go." 

He never hears from SD when she is over at BMs. No calls, texts, anything. She has her own cell phone. When SD is older I don't expect them to have much of a relationship sadly... unless she is getting Christmas presents. 

When OSD was around 16, DH practically begged her to join us for holiday celebrations on his family's side, telling her, "I would really love it if you would come" ... And so on. She threw a hissy fit and said "I'm not going if THEY are going." (meaning me and her step-siblings) Well, we are close to DH's family and they are planning for us all to be there so opting out for a spoiled-brat was not going to happen.

Fast forward, As we are sitting down to a lovely dinner, OSD calls her Aunt. Aunt puts her on the speaker phone so that everyone can say "Hello." SD starts bawling saying, "I wish I had been invited ... " Boo f'n hoo and on and on about how much she misses everyone and wishes she could have been there.

I was livid! Not only is she blatantly lying but she's also manipulating and trying to make it appear as if DH has tossed her away and replaced her with us.

I sat there and watched as no one else had much to say about it. DH explained that he tried to convince her to come and of course she was invited. DH's family just seemed to be baffled and showed sympathy towards DH. There wasn't much of a reaction to how SD is a manipulating liar and definitely no acknowledgement of how uncomfortable the whole display was for me.

That was an "Ah Ha" moment for me where I got to see the old blood is thicker than water in action. No matter how stupid or lying SD is she is still their blood and they will excuse her unconditionally. Also, they only get to see a glimpse of her in action in this one moment whereas I get to watch her manipulate and act spoiled day in and day out.

In that moment I decided to make sure I keep my feelings about her to myself and disengage.

Family will have to see who she is for themselves or not. My relationship with them is separate from her, best to keep it that way. Either way, not my problem. If they think she's so great THEY can hang out with her. I have the feeling a dose of living real life with her would cure them of excusing her terrible behavior but they may never get that chance.