Just a minor correction, you do not have to go for Robert right away, Lena can stop him at the kiss on their first date (or alternatively in front of her home), but Lena either breaks up with him or unavoidably puts out after their second date during Chapter 3 (you cannot just lead him on long enough for Lena to just keep her restaurant job).I don't think Eva should introduce new characters either, at least not at this point. It's just a pity that the characters available to Lena so far are all triggered in the same fashion: Immediate sex or nothing at all.
Robert and Mike you have to have sex with right away, if you don't give into Robert on the first scene with him, you don't get anything at all. Mike could still be a wild card, but he's a rather dull character if you don't fuck him right away too.
As I mentioned, Louise is in a emotionally charged state when you can trigger her, if you wanted something more romantic of her it's not unreasonable to reject her initially. Now though, after the bottle game scene I'm hoping there will be an alternate entrypoint into her path.
That leaves Ian. He's fine but I just personally dislike the narrative insistence upon him and Lena, so I rejected that path.
Ian on his own have had options to have a lot of sex, casual Alison, Emma, Cherry. While the slow build has been going on he's had plenty of opportunity to be just as lustful as Lena has.
I'm hoping something comes of Lena/Holly.
My hope if that Lena/Holly
You still get like minimal character development from Robert during the second date too (intentional since his character really is just a fucboi with very little depth) so it is still a bit of a moot point, but technically you don't need to put out right away to keep on getting content with him.