Stuck in the middle of a friend-web?

Not to downplay Nikki and Jack but you really need to grab the courage to talk to Dom. This is really about your feelings for him. The way you described it, it sounds like Dom doesn't even know you even think about him for real. So you should find an excuse to hang out with Dom...find something you're both into and go do that. As for Nikki and Jack, there's nothing you can really do about it because its between the two of them. Still be a good friend and listen and give good friend advice but that's really all you can do.