This does raise one of the real questions though: if the MC has 0 points with Kaija, did he actually love her? I'm inclined to think not. The two clearly weren't on the same page in terms of how they like being treated and aren't especially forgiving of the others' habits. Given the retroactive backstory at play, it seems likely the MC's attitude towards Kaija was as tepid as her attitude towards him.
It is very, very, VERY easy to get 0 points currently.
1-2 points if you're being nice.
Have sex with Kaija.
Get mad at her for leaving again (chuck it down to stress and yet another fight because she's always away)
Call or Don't call her while she's at work.
Tell her to be careful once she comes to help with mercenaries.
There you go, realistic relationship and yet 0-1 points, and hard "friend" route.
Even best couples fight sometimes, having 1 point doesn't mean MC didn't care about her.
You know how I got my "friend" route on 1st playthrough? By role-playing MC in a relationship that's going through rough period. Gave her call at work and told her to be careful during the fight.
I genuinely went into this one expecting to like her.
2 points end of chapter 1. "Yeah, sorry mate, you're just a friend to me".
And thus, my eternal love for Kaija was born.
Ceolag mentioned he's changing chapter 1 choice for sex, so it will give 1 point (I think that's the change, too lazy to search for that comment), so after chapter 5 is out those choices will net 3 points, which is love route.