It's nice to read what someone in a polyamorous relationship thought about Suwako and Touma. Also,
but I hope everyone reading these stories doesn't think actual polyamory works this way, as it wouldn't work at all as presented here."
I definitely don't view Suwako and Touma's relationship with others as polyamorous, because imo a polyamorous relationship works if everyone in that relationship is equal to one another (an example of my view of a polyamorous relationship is MakiRinPana's Lessons on Living Together!?) .
Like for example, Suwako loves a lot of people and they love Suwako back, but Suwako is the kind of person who just likes to give, give, and give whole lots more instead of give and take, and we see how that turned out for the MC.
As for Touma, it's not love since from what I've seen she just wants to make other girls become cute(r) while doing and saying what one would do and say to someone they love (as in romantic love). Chapter 2 showed that quite clearly.
And lastly, I agree with your friend that things can and will most likely end badly for Suwako and Touma.