I know this is clearly supposed to be a love triangle... But it's so unbalanced that the love triangle tag almost feels misleading
Honestly, I'm not sure the point is the love triangle, given how unbalanced it is. I think it's a coming of age story that's about how friends (and relationships) change over time.
When you look at it from that angle, the author signaling very obviously who is going to end up together isn't harmful to the story.