i love girl genius they went the funniest possible way with the love triangle (polyamory)
Even before it became clear that poly was a viable and indeed preferred option, the fact that Girl Genius was super uninterested in having the dreaded YA trope of "which boy do I choose oh no" be a major plot point/character motivation/source of angst/timewaster did so much to endear it to me.
Agatha's approach of "I'm not dealing with this. I'm busy. I have work to do. You two deal with it" is iconic.
And that the plot and the characters have been given time to deal with it - to drift into the solution everyone will be happiest with, quite naturally, because that is what works for them - is something that quite frankly should be studied in schools.
Oh, there's LOADS of trope analysis on Girl Genius Tumblr. Stick around. We do that. ;) I wish I'd tagged it consistently on my page so I could direct you to some of it; unfortunately all I can do is gesture to the whole blog and say "have fun".
Fellow aroace here. There are multiple points at which I fell flat on my face for this series, but this page right here...
...down I went. Bought my loyalty forever, right here.
I'm here for the OT3 - I am so very much here for the OT3, I want to see them get there and be happy (and terrifying), endgame or we riot - but I am also so very much here for the OT3 having work to do, and doing it.