I think you have to come to a decision what you find is acceptable and what you find is not....that is your personal choice and then become consistent in sticking with it.
It's hard when dogs don't completely get on, I have the same. We got Alfie 2 years ago (the ginger boy) and Finn was far from pleased....and he let Alfie know for quite a while...it was touch a go whether we would could Alfie to be honest.
We found that Finn just needed his confidence to be built up and trust that we would deal with the situation - we showed him that we would intervene if Alfie was in his face or stealing his stuff and once he realised it was us that decided who got what, he relaxed with Alfie.
I can only comment as to what we have done - it might not be correct but the boys haven't had a fight in months, if they are cross with each other now, it's just a bit of posturing and a growl so I think we have it right for us.....You need to be as un-reactive as possible if a situation arises because if you add shouting into the pot, you increase the heat. If the boys have words, we stop the situation calmly and lead them into a different frame of mind by diverting them away - 20 minutes later, they will be licking each other

If the boys growl at each other on the sofas, they are immediately put down onto the floor and we walk away from them....they've learned the sofa is for peace.
Certain situations will never go away, you just have to manage them.....Finn likes to try it on and steal Alfie's bones.....we calmly retrieve and give back to Alfie, pick up Finn's bone and put it straight in his mouth to re-affirm this one is yours.
It's very hard trying to keep the peace...good luck
