Okay, so main girls are relationships and Side girls are not?
And the Love interest is the main girl's and that route is non-dik or rather Chick route and reverse for side girls did I get it right?...
nope... wrong..
There are these main-LI for now... Jill, Josy&Maya, Bella and Sage
The affinity (chick or dik) is not that important to be in a relationship with them. But to start it... for Josy and Maya for example you need to be chick or neutral to start the throuple, if youre in it you can start to be a dik... how long this will work in season 3? Dont know, but for now you can be together with Josy and Maya as a dik, just not from the start.
You can be a dik and get together with Bella too, but need to follow some rules here... be always good to bella, dont fight Troy and dont talk bad about the food in the cafeteria, than you can be with her as a dik.
For Jill i didnt find any way to be a dik an win her over in the end... yeah you can start dating her as a dik, but in the end at epsiode 8 she will diutch you as a dik so far... didnt find another outcome as dik, dont now if there is a way. But neutral works.
Sage is pretty much free of affinity... dik works way better with her, but chick will work too.
Quinn is no main-LI i cant think of a way that she ever will become one... her story is just not made for this. But i get it that so many fans want her to be a LI but she will never be i think. But yeah you can get be with her in "someway" close. works best as dik, neutral works too... as a chick i didnt manage to get close to her.
For the side girls affinity doenst matter really... only your decisions, some of them will influence your affinity though... it depends heavily which sidegilr you want to go for, some need dik status for some lewd scenes, others not.
The "system" is not perfect, but it works pretty good... its obvious that Jill dont want to be with a dik, doesnt make sense to play a dik a go for jill in any way, same goes for Maya and Bella.
But overall, you can go for many girls with different affinity... but if you want to know if you can go for all of them in one playthrough, the answer is simple, no way. Only with cheats, but they will destroy your savegame with the very next update at least.