Ian,

It stinks but it is what it is. I haven't had a ton of dogs in my lifetime, but of the few I have had, this one was by far the brightest, very easy to train, very eager, good prey drive etc...lots of smarts.

She just has an iffy temperment is all. She'd probaby be great in a single household or with an exceptional trainer who is well prepared to handle her quirks...that's just not me and I don't think I could EVER feel settled with this dog in the household for the long term. Some of what I percieve to be fear-based aggression, food-aggression etc. at 18 weeks old has the potential for big problems when she's full grown.

It doesn't change the fact that I really liked her and I'm kind of heartbroken over the mess...best for us and best for her.

With a puppy...i probably wouldn't do that just yet.

I would wait till training is established and the dog is old enough to understand whats acceptable and whats not.

whats not to say that you let this pup on the couch now...and he gives you no problems..then at 6 months or a year...when he's coming into his own and might be prone to challenging your leadership. It might get to a point where he may start to try to exhibit dominance by not moving when you say or thinking that's his spot and not be willing to give it up without a bit of a fight or a snarl. Especially when I see you have kids.

I would wait....there's lots of time to bond with the dog on the couch if you prefer that.
Some dogs are the type of dogs that, when they are older, are constantly trying to move up in rank throughout most of their life. As long as you are confident that the dog knows who's in charge and won't see his spot on the couch as a sign that he's above others in the family then it's your choice to let him up.

again though...I would wait till the pup is older and understands where his place is among the "pack".

JMO!