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.