Banishment generally 'washes away' any negative energy that may float around. Meaning it'll banish any sort of negative energy, no matter if the energy is associated with your failing relationship, love, home, the environment around you, etc...
Energy is a general thing. If you banish negative energy, it means that you banish all of the negative energy generally. By saying all of the negative energy that floats around I mean to everything that happens in your life including your relationship as well. When you perform banishment you need to wash away the negative energy that floats around you, that's basically what banishment most commonly serves. Since the energy is such a general term, it means that it washes and touches all of the negative energy which can be the outcome of either your environment and either your relationship. By performing negative energy banishment you take away all of the negative energy by all means, not only a specific energy form, if that's what you thought. When something touches such a general term as energy, it gets influence all over it's various 'branched' (associations). It washes away all the negative energies that may be the outcome of whatever you may thing of... Energy is energy. The banishment basically washes it away. It doesn't matter to what the outcome belongs to since as I said, energy is general and it always stays energy.
However I believe you can be as specific as you want while banishing energies... In every banishment you perform you can choose to focus on only one circumstance of negative energy outcome, if you wish. Do what you think is the most reasonable thing to do. You can either focus on every reason in your life specifically and either perform a general banishment which will generally banish the negative energy that floats around you or surrounds you.