Well, she was the one who was assembling it in the first place, she is in love with mc, so she does act like she is in the harem. Refusing to sleep with her won't change her attitude towards mc and won't bring too much dinstance between them, just like with any other girl. No outsiders here, just less interactions if you chose "friendship" route.
Some interactions were kind of mandatory in the first part, the second one will be a bit different.