I think there's a neutral, contented space, and when we experience loss or other hardship we are into the grief space, and when we have something new or exciting or joyful we enter into the happy space. I think it's a continuum, rather than a binary state of being.

This question is getting into the semantics zone. Happiness is an antonym of the word grief according to Thesaurus.com. So if that's what you meant then yes your right. But if you are looking for a psychological or philosophical answer then the normal absence of any emotion like grief or happiness is called apathy.

You can be grieving and be happy. So no is the answer to your question. I once read that happiness was someone to love, something to do, and something to look forward to. It can also be said it is having meaning in your life. Meaningful for me is not going to be meaningful for others.

Is not that which was the source of your happiness that is now the source of your grief?

Oh, no. I was once clinically depressed and took anti-depressants. Yhey took away the sadness and depression, but made me emotionally dead. I felt nothing and it was horrible. It was worse than the depression.

There's really sad, relationship break, loss of parent or pet,etc and then there's joy of first meeting, acing a challenging piece of work. Happiness is in the middle. I wake up a happy person, or I use to til this arthritis shit started 18 months ago but still I wake happy.

For some being anxiety free would equal happiness.

Happiness has always appeared to me like a big colorful bubble while grief is that small, hard tangle of emotion that ties us down until the thread runs out.

Isn't light just the absence of darkness?

I think it’s the other way around- hate is absence of love because when you don’t love, which is fundamental, the void is filled w fakeness. It feels like a paradox might as well let go cuz everyone loves already depends on how much you decide to go w the flow and let go of that which isn’t. Like squeezing your fists at nothing. “Closed hands and open arms hold nothing” might as well be open and accepting. Easier said than done uhcourse

and neither of those are necessarily true..peace is the absence of struggle not just war...I hate peace...it is stagnation. The absence of grief is more than likely psychopathy to which there is no happiness.

Sure, by default, but that doesn't define happiness for me.
On a scale of 0 to 10, grief being 0, happiness being 10,
the absence of either would create a 5 imo or 'neutral', neither sad, nor happy.

No, that woudl be closer to contentment.

Apples and oranges.

No-life is not either/or. Not polar opposites. There is a middle field.

No soldiers have fun and laughter in war

No! Diametric opposites, or close (actually sadness is, which is subtly different from grief). You can be empty & not be grieving, you wouldn't be happy then. & grief, & even sadness, are necessary components to a fully lived life, just as happiness is. We all, or most of us, wish for more of the happiness, but can't avoid the other.

No. I am truly happy when the reality of my connection with someone or something smacks me up side the head. Even when alone there are so many varied and inescapable connections. Too often we suffer under the delusion of our aloneness. The removal of pain or suffering can be wonderful but maybe that's because pain and suffering cause us to turn inward making it easier to ignore those connections and get lost in our own minds.

.. and heads is the absence of tails! But seriously, this dichotomy only simplifies the condition. The passing of my parent gave me x units of grief. Chocolate ice cream can give me y units of joy. So if I eat enough ice cream, I'll get over the death of a loved one. I don't think anybody agrees with that.

Good grief! I hope not. ;0

In a nutshell, I think quite possibly, you have nailed it.
I don't think it's nearly as complicated as many make it out to be.

No. The two are not mutually exclusive.