What kind of nonsense is this?
Properly written explanation on why you don't like the game? Away with you. Can't have reasonable stuff on this site.
Joking aside, sorry to hear you didn't like the game so far.
I'll avoid talking about Kaija since my feelings for her are strong (in negative way) and everything has been repeated 100x already.
On other parts:
Why would he meet Kaija?
I'd attribute that to his father being kidnapped and him still being considered in danger.
He might be angry, but not wanting to see that topic resolved would be stupid.
Why go to Neverwhere with Kaija?
With you there, but that one was explained by dev. Simply put: his own time. Too much time investment to make alternate route there (there's a full post by Ceo explaining this one on this site, too lazy to search)
Why would he want to rescue his father?
Well, I mean...come on

This one is fairly obvious, and MC didn't have all answers by that point. Can't judge someone without all information. Once he got all information, we, as players, got the option to tell family to fuck off. Supposedly, this means family is gone gone. You actually can cross them off of your list.
Why would he go to Alfar (elves) after his father was rescued?
To paraphrase Pitch Meetings: "So the game can happen". Realistically, once his father was rescued and he had chat with his family, MC really should have option to just tell them all to shove it and leave. As in, get the hell away from those lying cunts and create new life, with new people and honest relationships.
But that wouldn't make much of a game. Unless made as some sort of alternate ending or such. Very few games do that, it is once again lots of extra work for no real gain.
For LIs, well, I have no problems with main and secondary LIs. Plenty of VNs do that, you can screw around, then pick one of main LIs or stay single in the end.
Minor note: sunk-cost fallacy sucks, don't get stuck on things you're not enjoying. There's a VN on this site most people would have in top 3 overall, I can't stand it. Dropped it, have no intention to go back.
If you don't enjoy something, don't force yourself to play it.
Based on your post, you didn't enjoy story, don't like characters, don't like certain situations which exist to move plot forwards. Just, well, drop it and move on.
And I'm not saying that in angry way, making honest advice. Best of luck