My friends are dating each other
If you really honestly feel like they’re leaving you out, then you say something.Approach them either separately or together, whatever you feel more comfortable doing, and just say that you love both of them and you’re so happy for both of them, but you feel a little left out.You have tried to confront one of them but it didn't make any difference so let it be until it's not affecting your friendship with them.One reason I can think of regarding your concerns is that you might be interested in one of them. If this is true than you need a different question here.
Clearly, the roomies aren't going to cut ties over this, or there'd be no TV show—but I'm looking forward to watching them figure out the situation.
They've met enough other a couple of times, at a couple of parties I've had, but since they live in different states (with me literally in the middle) they'd never run into each other without me inviting them both out.