Responses
Except it's not really polyamory; it's a love triangle/threesome. I seriously doubt this author put any consideration for a real poly relationship (since this manga is /that/ shallow). The semes are more begrudging rather than consenting to their relationship since they don't want to run the risk of losing the m.c to the other guy.
Polyamory (from Greek πολύ poly, "many, several", and Latin amor, "love") is the practice of or desire for intimate relationships with more than one partner, with the knowledge of all partners.It has been described as "consensual, ethical, and responsible non-monogamy".People who identify as polyamorous reject the view that sexual and relational exclusivity are necessary for deep, committed, long-term loving relationships