@SuperOniichan: To be fair, I didn't *seriously* consider the romantic angle, just which character I like more/which kind of interaction I find more hilarious to watch.
If you want to look at it more seriously, then I'm pretty sure that we won't see a f/f relationship in this manga, and Sonobe x Shiraishi sound like the least unhealthy option, IMHO.
Also, I'm a huge fan of friendly triangles (as in "all three love each other" or "two people love the third person and like each other"), which is a thing that happens almost exclusively in fanmade or indie stuff, unfortunately...