Sadly I've done all those. Given her the phone and dumbell. The phone hint says to follow her home after working out which is what I've been doing but can't seem to get past the BJ the scene. Reading up I think a pervert or someone is meant to attack her on the train or on the way home and the MC is supposed to intervene and it doesn't seem to be triggering.Did you by any chance try "find girls" -> "Lina" when at school?
Seems to me like there was some route that I expected progression to be done (to me, "logically") in one place, when the game was written to progress elsewhere. I don't think that was with Lina, but it might've been. (Oh, and did you already get the dumbbell from the pawn shop and give it to her? That might be needed, as well.)
edits:
Other thing to check: the phone, go to characters, click on Lina. There's "hints" as to what needs to be done next... sometimes they're much more "direct: go to X and do Y" but it might help.
It's been a while, since I did any of that, so I might be wrong. I kinda (to borrow a term from the discussion a few posts back) burnt out on the story lines. None seem to be going where, or how, I was hoping/wanting them to go. And then there's the whole "no turning back" decisions in a few places that... well, instead of a couple of "are you sure" screens, a bit of forewarning of how those routes go would've been much more useful. (But, that's probably on me for not looking/checking posts on here.)
I'll just try and keep going with other charcters route and see if something needs to be done before it finally triggers.
I'll be honest I haven't been actually following the charcters in what you would say is a normal way so im hoping my save file isn't fucked. For instance I started the gym challenge with Lina/Alice but never actually saw it through because my dumbass corrupted Alice first and got her fired from work and split from Will lol