I like to know those who my partners are dating but I can't imagine going with them on dates unless it was someone who I was (or hoped to be) involved with as well. But then again I tend to feel like I'm invading people's privacy when I stumble upon things that *I* don't think I should see/know even when it's completely out in public. There's an intimacy about dates that has it's own energy and I feel like if I was there on a partner's date that energy would be disrupted.
Everything will be ok in the end. If it's not ok it's not the end.