is she doing anything disrespective or are you just not wanting her around because she biologically isn’t yours and that makes you uncomfortable?

Is she always hanging around the house, is that what makes you crazy? Seems like your little kids would drive you crazier.

Can she take the little kids out somewhere so you have alone time?

Why can you not go out and do things without your husband?

attends school, works, is helpful, adores her little sisters and generally sounds like a good kid. So it sounds like this is a you issue and not a her issue. You could ask her to babysit so you can go out. You could ask your husband for date nights and ask her to babysit. You could hire a sitter and do the same. You have the power to have a social life. 

In terms of your SD getting a social life, it takes time. Especially at a community college where the age range of students varies and most also work. 

I also agree that this issue is more to do with the OP vs her SD specifically.  OP doesn't want the extra person in her home.  She seems to feel limited and I am thinking has a loss of privacy as a result of the girl's presence.  What she wants is for the girl to not be there.. but the girl is her father's daughter.. just as OP's girls are hers.. and it sounds like for the most part the 18 yo is not doing anything that would be objectionable.. except for the fact that she exists.. and OP doesn't want her there.

Now, there are options... but they would come at a cost.  Would OP be OK with her husband helping the girl find another living situation.. perhaps with others her own age?  That would be more money..but she would have her privacy and home back as she likes it.  She mentions that the girl does work.. not sure if that money is going towards her education.. or not.. or whether it could help fund at least part of a roommate situation.

It sounds like the SD is a bit introverted.. and new to the area so hasn't had a chance to meet people much yet.  Perhaps dad could pay for a membership to a gym... or fund her joining a kickball league.. or some other extracuricular activity.  I think OP may be forgetting that it isn't easy for everyone to make new friends at the drop of a hat.

Now, that doesn't mean that OP needs to be arranging her household around this "kidult"  She has school.. a job.. OP needs to only worry about planning things for her girls.. include the SD in meals at home etc.. or inform her when they will not be there for meals.  Also, maybe SD should be babysitting a bit for OP and her DH so they can get out together to do some adult things?  I'm not sure what responsibiility OP has for the older girl anyway?  she should be 100% able to care for herself.. and if anything should be making things easier for OP.. but I think it's the mental view that SD is an invader.. that is causing the problems.

If it's not possible to have her DH move the girl out and pay for an alternate housing situation... the current situation maybe needs to be adjusted so that everyone is more comfortable.. but that also means OP would compromise as well.. just unilaterally saying she doesn't want the girl there with no real reason other than she just doesn't like it.. isn't particularly fair to DH or SD

I get what you're saying about the houseguest thing. Even with people I love and want around visiting after awhile it's enough and it's just kind of a relief and more comfortable when they leave. It's just not the same to live with someone that you dont have a certain bond and comfort level with even if they are polite and helpful etc.

The not being able to go out without SO sounds like a separate issue though. You need to be able to do that no matter what to have a healthy relationship.

I think some commenters are missing the point. It really doesn't matter how 'nice' SD is. It's extremely difficult and uncomfortable having an interloper in your own home even if it is DH's daughter.

Momo, I have SD(almost17) living with us full time now. I can totally relate to you wanting some alone time with your husband to watch TV or just hang out in the living room. I bought a TV for SD's room so if she wants to watch a show, she goes there. I find it stifling having her around all the time so that was one workable solution for me to get a little peace in the evenings.

That might sound mean but she isn't my daughter and I don't want her around me 24/7 listening in to every conversation I have. It is like having a weird, introverted housemate that I feel utterly uncomfortable around so workable boundaries were introduced to stop me going insane!

she never wanted to watch the TV in her room at all but still sat with DH and I. I asked DH to spell it out for her in that we need couple time ALONE after dinner in the evenings and hanging out with us all the time wasn’t an option.

In an intact nuclear family they may all feel comfortable hanging out together but in a blended family there needs to be a greater awareness of other people’s space and to not be up in it all the time. 

Took a long time for SD to take the hint.

I get it. Skid24 just moved back in and has never lived in this house with us. It’s a little strange and I prefer if he wasn’t here. At least this house is a 2 story house with a living room with TV on the main, basement with a bid screen tv and a large bonus room on the second floor. When we did up the rules before he moved in, it was stated that the bonus room (which is right outside the master bedroom) is off limits to skid. I wanted one tv room that was ours only. 

DH did want it in there, but I reminded him that in the old house we has a loft with a couch and tv that was off limits to all kids and I always want a room of our own besides our bedroom. He didn’t fight it anymore. 

One room that does not smell of young man, and no skid mess and privacy. Otherwise it would not work for me. 

So far skid stays in his bedroom in the basement and watches tv, fine by me. 

Yikes that would be a nightmare for me. Maybe suggest she live on campus so she can try make friends and not isolate so much? Would be healthier for her if she got out there more, plus if the dorm is near you she can still visit and have the safety net of you guys. Could be a positive for both of you. But I guess you’d have to convince your DH of that.

OP, curious George is NOT a stepparent.

Was seriously thinking of paying the 14 1/2 year old stepdaughters bum mom myself just to take her kid back. So we can be together. Keeping 2 separate houses now until she turns 18. I don't want to live with her

Your DH is a problem. Why can’t you go somewhere without him or hang out with girlfriends sometimes. It’s abusive to not allow one’s wife to do things without him. I’d not tolerate such nonsense. I understand horror of living with adult SD, but I dont understand not being able to go anywhere without DH. 

I can totally  sympathize with you. When my DH and SD moved in two years ago it was a hard adjustment. I had been living on my own for the last six years. Then it was like a double whammy having to get use to living with a man then on top of that a 7 year old. He worked graveyard so I was left stuck taking care of this little girl at night and could not continue my normal life. I felt I lost all privacy and alone time.  I understand I had to make sacrifices but it was still hard.  What I came up with so I could have some alone time was to send her to bed at 7:30.  Till this day I still make SD9 go to bed at 7:30. And the times she wants to hangout in the living room when I need alone time I tell her she had a nice room filled bunch of toys and books where she can hangout. The livingroom is the only place I can be alone or in my car. Its gotten a little easier I no longer suffer from depression due to this huge change in my life.