[IFeelGood]

I am wondering why D said that dating J would be a bad idea? Is it possible that he might be interested in more than a friendship with you?

I understand that they are all roommates but why not get J out alone? Invite him to go for a walk or for coffee or something...

And regarding what you said
"I've started a couple of other threads and for those of you who have read my other threads, it looks like I give off the tendency to spring from dating one person to another, usually resulting in disaster."

my other thought is... maybe just try a friendship thing with J without the others around to see how it evolves. Give yourself time and get to know him better...