Men's Promise Rings

Okay so I've been with my boyfriend for 2 years and best friends for 4, he has issues with reading signs (but it never means he doesn't want the same thing) and we know we aren't ready for marriage yet but we both want to be together. I can get him a promise ring right? I know it's usually the guy who gets the girl a ring and whatnot but I'm not proposing and it's just promising to be faithful and all that jazz. I'm not very traditional, and id consider myself a feminist. I think he will love it but I'm having doubts because I know his mom oh too well and she'll hate the idea.. (1 because she thinks we're too serious too young, and 2 because she would say it's him who should decide when and how promises are made). I should still do it right? I spent $200 on a ring for Christmas and I'm just having doubts like I said..