There is a point early on when game tells you to be very careful over next two days, if you missed something things don't work.I'm stuck at 33% with Melinda and the walkthought doesn't help at all.
I do'nt know if it's the sunbathing (she yell at me if put it out and slap me if I masturbate) or the 14:00 scene in the bedroom that is a problem but I cannot go further here.
EDIT: In the walkthrought, when talking of the v7, I have "cynthia shows up", something that hasn't happen yet. Is it consistent to that 33% ?
on my first play though, with a walk through, I had same thing happen no sister visit, repeted scenes with Melinda, over and over. I thought I was good after Vrs 7 I believe, but I was not.
Don't do anything stupid or vulgar with her she will react. ex. bedroom groping etc. take it slow real slow and then slow again, grind, grind. Eventually she comes around but still does not like aggressive.