Well, she might be the reason I play this then.
But hey, if more are added at some point, I certainly won't complain. lol
That said, is it possible to not lewd characters you don't want to? Or do you have to do all the content?
-Spoiler warning for everyone not wanting those!-
It depends how you play the mc. I know there's a dwarven character you can miss if you choose the wrong reward for a quest. You can also miss an Elven character by just not talking to her after your initial meeting. I believe you can get one of two other Elves killed during one of the quest lines, but I've never done it. Twig you currently cant save, but will be able to later. If you choose the wrong option with Cynthia then she stops talking to you, the same can be done with Zenalith, or you can just starve her to death on one of her routes. Last skippable one I can think of is Thea, you basically just choose to leave, or watch her get assaulted and murdered instead of rescuing her.
I mean there was talk of adding 'evil' variations to the routes at some point, so who knows? Bloodbath run perhaps? XD
I'd suggest trying to trigger the Pete events and possibly Thea's events as quickly as possible. If my theory is correct, then you shouldn't need anything else yo clear the current main story. Heck, it may be that you don't even need Thea's story. I do know that Pete is one of the key components though.
Actually now that I think about it...
The goblin slaying quests with Eve and Sander needs to be completed, and the delivery quest (regardless of if you save Thea or not). You also probably need to do Gabe's events up to the exam, and the first training field event with Talia where she kicks your ass. I know at least the first two of those have pieces of the main plot in them, so I'd say they are essential. I'm not sure what triggers the final story event of the current story though, but Pete is definitely involved. His events are mainly; eat a fish, get his help with some paint, tell him you've hit bronze rank. Possibly some more that Im forgetting. Then the final one that ends the current main story.
I think a good indicator that you're close to that final one is Talia asking about your sword, the stating that she's going to try find time to visit him.