Did you save Holly when she got attacked at the Mall at night, or did you let Patrick handle it? If you've seen that event at all?
It should happen first time you can talk to her at Mall at evening/night, choose "Go for a ride?" she declines but gets attacked. From then on you can gain Affection with her by offering rides, provided you stepped in and saved her.
You need a certain stage of affection before she even consider having sex with ya.
Offering rides is a bug free affection grind, go for a drink has the "map icons locked on screen bug".
If you haven't seen that attack event, it may be because the first long long while she won't even give you the time of day to speak at the Mall, so if you missed it and by then "messed up", be sure to try to talk to her every evening/night at Mall when she is there, after completing other stuff, one of those other stuff is the trigger I think.. or perhaps a conversation with someone about something...