My boyfriend and I have a 15 year age difference. We still love each other and work as a team and have been together for well over a year. As long as it's legal, it's a healthy relationship, and the two people really love each other, then age shouldn't matter. Also, as long as they're not hurting anyone I don't understand why it's bothering you so much. It seems strange you would let their choices bother you like this.