She's wanting to pay for both cellphones so they will be in her name, and the bills will come to her, and so HER bill won't come to YOU, specifically.
You can't stop her from doing what she wants to do with hers (and it's in fact GOOD that she pay for her own, since she uses it to communicate with OM), but you damned sure shouldn't get YOURS set up in her name and paid for by her.
You did fine. The "that wasn't my intention" line was PERFECT. If you really DO feel like you are ever a d*ck, don't be afraid to apologize -- briefly and ONCE -- about it. Take the higher road.
