I don't know if I'm going to be helpful or not. I've got a bunch of links, but I haven't listened to a huge amount of their catalogs, so the majority of their songs could be about love anyways (it's mostly pop/rock stuff, so it's a safe bet that they've got a bunch like that). Zoe Keating (although she may not count since she doesn't sing, as far as I know)
Heart
Stevie Nicks - Edge of Seventeen
Kawehi - Heart Shaped Box (Nirvana cover)
Pomplamoose - They have a lot of covers, so I don't know if your roommate will accept them.
Allanah Myles - Black Velvet (This one's kind of borderline. But it's a good song, dammit!)
Janis Joplin - Ball and Chain
I've saved the best for last though - JANELLE MONAE (okay, so it's from a concept album about an android in the year 3000 that finds love which has perpetually been on my 'to buy' list, but there's enough non-love songs on it.)