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I get a strong sense of balance, yin yang, female/male from this painting. I see the representation of balance with the dichotomy of day and night in the sky, the shape of the glasses, with man and woman in the glasses on the table, the grain of the wood, and the difference in topography of the mountains. Each side of the painting is similar yet not an exact mirror representing the push and pull of what can happen in life. We wouldn't be able to have one without the other.
Both the lotus flower and the waterfall/ocean help tie the sides together by crossing over the boundary between each side. Lotus flowers usually represent life and the layers of life. It wouldn't be able to thrive without day and night or without water to nourish it. Yet, in itself, it's representing both life and death as it looks like it's been cut and plucked from its watery home before coming to full bloom and placed on the table between them (you can even see the small puddle of water left next to it).
The waterfall is also at the convergence of the two sides suggesting that it is the point at which the two can come together and fill their glasses and to thrive together. If they do this, an ocean of opportunity awaits them and if they miss their chance, it's okay because the ocean is large and there is always another opportunity as the waterfall will always keep flowing.
The two sides may be different but require the same source of balance for survival. The man and woman are already toasting each other in acknowledgement of their existence and importance to the balance. The glasses seem to be a part of the man and woman which I take to mean each glass is more of a representation of their life and the need to fill themselves up with life and the balance that comes with it rather than acting a glassy prison BUT, life can be a type of prison if you are unable to find the balance. You'll end up looking out into the world from an empty cup. The waterfall of balance can seem far away but maybe it's only an illusion. Maybe it's right there and all you need to do is stretch your glass and and catch it in your cup.