Are you seriously asking for a trigger warning on poly relationships?? Bro ðŸ˜ðŸ˜
In a game where you're playing as the main character, in a genre where people frequently self-insert, yes, it makes sense to let people know ahead of time what kind of relationship it is. Most people are not poly and not everyone enjoys self-inserting as a person engaging in a poly relationship so it is perfectly fine to ask for information to avoid a route they won't enjoy.