Your roommate may not be totally wrong, but make sure you speak to the Lady in depth about it.

I am not polyamorous, but a good friend of mine is. And I have seen a few other people try to convince themselves that they could be polyamorous.

The key to any good relationship is communication. When you enter a polyamorous relationship, either as a muti-person unit or as a couple with some open rules, you now have to be sure you're communicating with EVERYONE. More persons involved means more chances of someone feeling left out or feeling suspicious of un-agreed upon behavior.

Yo have to communicate and discuss relationship expectations very early on, or chances are someone will feel like they're being mistreated.

A lot of younger people entering poly relationships think that it's just a way to sleep around a lot without actually cheating, they don't realize that they're going to get jealous.

Jealousy is a MAJOR thing that will bitch-slap you even harder when you're partner doesn't feel guilty being with someone else. Even when expecting it, it's a hard thing for a lot of poly people to deal with.

Just a few things I've noted looking in from the outside, so take it with a grain of salt.