I think it's pretty apparent Jen's always been "the main character" - I dont say that to piss anyone off, but she feels like the "canon girlfriend" compared to the amount of progression with the others.
Though as Lea's grown in popularity she's catch up.
Oh yes not the end of the world, devs pick what they prefer for their games/VN and I guess on top of that also what proper supporters prefer, it's also exponentially difficult to move forwards stories like this if every single character ends up getting tons of content.
Imo the "main canon" one is Emma, have only started a 2nd playthrough but can already tell she's probably avilable as dom, sub or neutral, right?
Jen is the clear 2nd, with all the extra added "baggage" of the MC's previous situation
Everyone else I imagine depends on what patreons/backers/supporters prefer?
Again I'm loving the game, but going for a 2nd playthrough I already understand why Olivia is becoming popular, interactions with her are interesting
My "issues" with Deb is not the quantity of interactions btw, she has plenty (lewd and not), it's more like at a certain stage they pivot from being something more than simply run-of-the-mill mistress/sub inetraction into... well just that
And outside of that (meaning outside of the Femdom/Sexual scenes)... nothing she becomes (always imo) blander than the ones you have turned down (e.g. in my 1st runpretty much everyone except Emma that kept ending up in my face... also literally haha)