Yeah, it would be a long boring life without love. 'Cause without getting attached, without having fun -- what's the point?

And that comes back to Boe's affection for his priests (and theirs for him).

My feeling has always been Ianto is to Jack as Jack is to the Doctor, but they are definitely 'equalizing' and changing and growing. Right now, at least, Jack's attention is very much Ianto-ward.