Speaking of the many meanings of "roommate", here's a webcomic. Okay, to explain, after Megan and her first boyfriend (not shown) broke up three years ago, he's been considering some "lifestyle changes". Now her roommate Jane (not shown) was invited to his wedding with his new boyfriend Bruce, and Megan's her plus one.

http://bobandgeorge.com/Subcomics/SuperHo/Archive/ho166.jpg