That’s a wide open question, Big Sis, and I’m pretty sure it’s far beyond my pay grade, but I’ll give it a crack. There is a reason most relationships aren’t open. No, it’s not herpes. It’s an issue of trust (and herpes sort of falls under that umbrella). In a traditional relationship, the underlying assumption is that each person loves the other more than anyone else. That may not be a problem on a desert island in the Pacific or in a bio-dome in Arizona, but it’s a sticky wicket when you’re working the light meter on an American Apparel photo shoot – and truthfully, most colleges look like an American Apparel photo shoot, so college is not the easiest time to declare your undying love.
Even if you do love your partner above all others, that doesn’t really mean much unless it’s manifested in some tangible way. You can’t just think it. You can’t just say it. No, you have to prove it through sacrifice (the folks in marketing would call it “bliss” - and you should too if you’re in a relationship): Taking out the trash; wearing that sweater; looking up where the clitoris is located. Short of some sort of dramatic martyrdom (I’m looking at YOU, Jesus), the best way to truly prove your love for someone is to, as the Bible says, “Cleave unto them until death do you part.” That’s a heavy-ass burden of proof, and even then there’s still room for doubt.
There’s the problem: How can you trust that someone truly loves you? Are words enough? Or do you require that their actions back up what they say? I think most people would say yes on the latter, which makes an open relationship a very difficult thing indeed. It’s the kind of relationship that requires a huge amount of faith, trust, and self-security – and most people fall well short of that mark. Your brother and his girlfriend may not. They might actually be able to make it work, and they will never know unless they try. Just let him know you’re there for him, however it works out.