I have three paths I play, and go back and forth as to which one will be my head canon. I'm telling myself I'm leaving my options open since I would guess Eva has a few curveballs left to throw.
1 - IanxLena, with the goal being the Holly Trinity. Ian and Lena got together early, though Ian had a little fun with Emma first, and Lena tried out Robert but decided she didn't like being pressured into sex. They're both close with Holly, and encourage her to be more open, though not to the extent Ivy wants. Lena does kinda like being a dom to Louise, but that development came later than it could have, though she brought Louise to Ian for a threesome. She gets weird vibes from Stan and while she has no need to antagonize him, she doesn't want to have much to do with him. Lena enjoys hanging out with Ivy but wants to just be her friend, though she thinks it would be hilarious if Ivy and Jeremy hooked up - and she did tell Louise Jeremy was cheating on her. She's pretty okay with Stalkfap (and it turns out Ian is too). Lena was initially interested in Seymour's offer, and did a session with him, but got suspicious and didn't sign the contract. Ian went for Emma initially, and instinctively knows Alison is yandere. (If there's a threesome option coming up with Lena & Emma, Ian is all for it.) He supports Perry with Cherry, and does his best to help Wade and Cindy keep their relationship together. Ian is over Gillian; Lena is over Axel, and flatly wants him out of her life. Ian couldn't give a shit about Minerva and antagonized her all the way, and also went over her head to get his book manuscript to Seymour. He went to the book event with Holly and kissed her, but nothing else happened. Lena has also kissed Holly and is attracted and confused.
2 - IanxHolly, Lena the Slut. Ian and Lena liked each other, but Ian really clicked with Holly, and after a brief fling with Cherry, Ian got together with Holly at the book event and hasn't looked back. For Holly's sake he has done his best to make nice with Minerva, even though he doesn't trust her. He's over Gillian, supports Perry with Emma, tries to keep Wade and Cindy together, and Alison is passed off to Jeremy, who he's close with. He's excited about his novel and writing for Victor. Lena sleeps with Robert and Mark, blows Marcel, and steals Jeremy from Louise, because fuck her. She deliberately gets close to Stan, partly to piss Louise off, partly because Stan is so easy to manipulate. But she's not over Axel, and she loves the feeling of surrender she gets with him and with Seymour (and the money she can make). She is slowly spiraling out of control.
3 - Lena's Lesbian Harem, Chad Ian. Ian and Lena liked each other, and Lena toyed with Robert for a while, but Lena is figuring out she's really into women: Holly, Ivy, Louise, she wants them all and has designs on Emma next. She breaks up Louise and Jeremy, she lets Ivy corrupt Holly and they have threesomes, and she pressures Holly into sex with Mark (and soon, Robert). She's over Axel, and Seymour doesn't get even a first look. Ian thinks Lena is sweet, but is totally into easy sex with Alison (and a threesome with Jeremy, his eskimo bro), seduces Cindy and is stringing her along, and initially hatefucked Minerva but lately has been nicer to her, while still screwing her brains out. Writing is for innocent nerds like Holly; Ian bulks up at the gym with Jeremy and is set to go as far in the MMA tourney as he can. A little evening tussle with Ivy is also welcomed. But he's not over Gillian and is fine with getting a little sex from Jess in exchange for a bed for the night. If his actions mean the end of his friendship with Wade and Perry, that's fine because they're losers anyway.
I have these three partly because they're enjoyable (in different ways), but also because between the three of them I get something like 90% of the gallery scenes one way or another. I know the gallery is unlockable from the start now, but it was satisfying finding a way to get almost everything in a limited number of playthroughs.