I almost get the feeling Sarah may go this route too. As in, not being a Main LI (M&J, Sage, Jill, Bella), but a side romanceable girl that has an ending. A lot of other games have side girls that have endings, so hopefully that'll be the case
At the HoT house when decorating for Christmas and have been with her to that point, you can go down to the pool room for a lewd scene. You can start off with an optional kiss with her. After the lewd scene plays, she'll kisses the MC if you kissed her at the beginning of the scene. They both then walk away from the pool room and scene arm in arm smiling.

Seems like, if you kiss her, there may be more than just sex involved....
Mel, I'm torn on as if you get the lewd scene with her at the decorating party it almost seems like she might have an interest in MC. But not sure if it'll be side-girl calibre.