I used to think that grumpy and abusive were different things. Perhaps they are, but as I've lived my life I've realised that every single person I've come across has defined their 'grumpy' partner in language normally associated with abuse.
If you find yourself having to regularly modify your behaviour to accommodate the moods of another, it's unhealthy.
I am exceptionally good at regulating my own mood so that it is not affected by those around me. And I have found that the only times I've had to really concentrate on maintaining that is when I am with someone who cares nothing for the effect their own mood has on others. Otherwise known as a selfish arse.
We all have bad days. When we are with those we love, we should be able to say we're having a bad day and expect support. That is NOT the same thing as going round and making everyone else uncomfortable. If you can't get away with that with colleagues, don't expect the person you profess to love put up with it either.
If you're having a bad day, decent people who respect the fact that they are not the centre of the universe talk about it to gain support/reassurance or burn it off at the gym/down the pub, etc.
We all have off days. We all overstep the line sometimes. THat's human and normally easily forgiveable in the context of a loving relationship. But if you find yourself having a bad day every day, it's probably time you got some counselling or changed your life in some way. It's not ok to make everyone else miserable too.