To help shed light on the 'canon' of the Ultimate universe's version of Sue and Reed's relationship, here's a quote of a discussion between them, frum Ultimate Fantastic Four #7:
Sue: Someone's avoiding the bioscanner, Reed. I need your help.
Reed: Is it Johnny again? I can't talk to Johnny, you know that.
Sue: It's you.
Reed: I have too much to do. I feel fine.
Sue: We all feel fine. Even Ben's troubles are psychological, not physical.
But I need the data, Reed.
Reed: You three are more important.
*At this point, Sue looks really pissed off and then spins Reed's chair telekinetically around so that he's actually facing her instead of the microscope*
Sue: You are important to me, butthat.
Furthermore: I am a biotechnologist.
That means you don't get to make out with me without sliding that skinny body of yours into my warm little bioscanner.
You may be the king-poop breakthrough physicist here, but you do not understand bodues the way I do.
So you can stare at Ben's scans until the sun goes out, but you won't figure anything out better than I can.
And I need to make sure you're not going to die, Reed.
*One frame of silence*
Reed: Can we make out afterwards?
It's just that I think I'm getting good at it.
Sue: *kisses Reed* You started out good at it.
You're getting fantastic.
*They start walking, Sue pulling Reed by his hand*
Reed: We're going to make out now?
Sue: Bioscanner first. Playtime later.