Yeah, 9 chapters in, Ian and Robert are the only guys who have asked Lena out on an actual date. Little-known secret about women -- they like going on dates. Like, a lot.
IMO this has to be an intentional choice, for reasons that may or may not become clear. In GGGB, the MC has male suitors who actually ask her on dates and activities, alongside all the freaky perverts she can get down with. So this omission -- in a female-authored game -- seems purposeful.
I think one way to interpret this is that the story isn't about Lena going down a corruption path. She's already corrupted from her relationship with Axel, and Ian or Holly are her potential paths out of it. EK seems to have cut this, but in the older releases Lena could steal money from the cafe. To me that was a clue that her character was intended to be more ambiguous than initially meets the eye.
The other way you could see it is as a limitation imposed to make the Ian/Lena relationship plausible. Like I said, Robert is the only other character who actually acts like a potential boyfriend. But if you go on a date with him and talk to him, his responses are comically bad. Obviously intentional, to steer you away from a relationship with him. If EK gave him any personality at all, Robert -- or any similar character -- would start to look like a better option than Ian, because he's not trying to bang 5 other girls.