Totally unattractive in my opinion.
But its what you think that is important..
Imagine the fun when one of them gets caught on clothing or a bra or whatever.
Your B/F sounds god damn selfish.
eewwwww.. nipple piercings.... ewwwww...
don't get it done for your bf.. you may regret it..
don't get it done full stop.. it's ewwww... even more so on a girl... ewwwww....ewww.
If he just think they look nice, get some magnetic ones or something. Well, you can get magnetic earrings, anyway... I'm not sure if a magnetic nipple ring would work...
my gf has one and i fink its bloody gross
huuuuuuuuuuuuuuuuuuuuuuuuuuuuge turn off
errr not nice but they look good