Open relationship?

So my boyfriend and I are in a long distance relationship and it's been like that for over a year. It'll probably be a while before he'll actually get a chance to come visit. Lately he's been complaining about "blue balls." So I've been thinking about suggesting the idea of an open relationship, I guess. I'm not sure what to expect, if he'd agree or not. I just feel bad that I can't really do anything to help him at the moment. But, I'm also worried about what might happen if he does accept the idea. I'm completely clueless about what to do, or if I should even consider it as an option. I know I won't enjoy him being with other girls, but I also know that he has needs too and sometimes masturbating isn't enough.