I really need help!!

Welcome!  Please do not give up on your boy.  We rescued an abused BMD at 3 years old.  He was painfully shy with humans especially men.   My hubby is loud even when he whispers, lol,  Hot Shot would run if he spoke very loudly.  He didnt misbehave but it took us well over a year of petting loving "quietly" coaxing before he was finally comfortable.  Now he is the king of the castle so to speak.  When you dont know what the former life was, it is hard to know how to fix it.  We found out very quickly that he was extremely scared of thunder and can predict a storm within about 20 min.  He is also scared of gun shots and loud noises.  He came to us at 3 like I mentioned and Rocky our lab mix was about 5 months old and we adopted him at approx 8 weeks old. 

When he first came, I walked him on lead, around our property several times a day.  We live in the country and most of our dogs are free to visit each other.  Knowing he would need to know his boundries this is how we tried to get him from running too far.  He tried a couple of times but after a while we could just call him back and he now knows how far he is allowed to go.  We have at times wished that we could have gotten him a little younger for training but really he is very smart.    We didnt push him but encouraged him with routine and love.  Now the only thing he doesnt like is taking a shower :)  I havent given up hope that I will even convince him to like that as well.  I am certain he will never get over the fear of thunder storms (found out later he was in a metal building as a pup during a tornado) but our friends here on the forum have helped us with some calming herbs to make it more bearable.

It may be a puppy thing, I am sure your girl will put him in his place if he gets to out of line :) us girls do tend to do that Mother thing.

Lucky Trooper to find a family that cares!

It sounds like he may be playing with her but doesn't understand her signals to stop.  Seven months is still a puppy.  Why do you think it might be dominance or sexual?  How long have you had Trooper?

I would suggest you don't throw these two dogs together if your female is not enjoying the interaction.  Start by crate training Trooper and don't let him have the run of the house.  He needs structure and time to learn the house rules.  

I'm very puzzled why you think he might be beyond help.  Maybe you need to give us more details because nothing you've said makes me think he's a lost cause. 

Both Jackie and Ginger have given you awesome advice -- Much of this comes under the heading of "management" -- meaning not letting him have complete freedom until you have his behavior where YOU want it.  Making sure your girl is protected (she was there first and doesn't deserve to have him drive her crazy).  Life may need to 'change' a bit for everyone while you train him, but as Jackie says nothing you've **sad** sounds unmanageable.  But tell us more.

McKenna1

Trooper is Nipping and biting at her legs and under her belly..she growls and moves away from him just to have him do it again.

I'm not a Bernese mountain expert but it sounds like he is trying to herd your other dog. Berneses were bred to herd stock and it seems that his breed is kicking in. I think it's time to start looking for a "job" for him as they are working dogs.

You can start by walking him everyday with a backpack so he feels he has a job to do. You can look for Bernese Mountain Dog clubs in your area who organize activities for this specific group.

 Care to elaborate? Nothing you have said implies that this dog is unmanageable.

As for him running from you, didn't you say you've only had him since 2.11? Give it time, he doesn't even know who you are.