Polyamorous is a person who likes to date multiple people at once, "coming out as polyamorous" to your partner is basically admitting that you've been cheating on them
"Yo I wanna date you but just to let you know I'll be dating other people too"
"Well that's not a problem"
Even in gta san andreas if your girlfriend finds out that you date another girl, she gets mad
that’s lowk something you have to tell them at the start, and if they don’t want that, then you have to either respect their choice and stay together or leave. it’s not just a silly “oh look i’m dating five dinguses!!!” it’s all about agreements.