It is almost impossible to find a true black. you are going to find that in certain light the color will pull out others like navy and plum. embrace it or paint it.

On my screen the pinterest picture looks a slight grapey color. Yours does too except a little more to the blue color. You can get black in any color. One issue I see is that you have the dark vanity. The pinterest has a lighter wood throughout. And the pinterest wood is somewhat yellowish and looks good with the purplish paint. Your dark vanity has some yellow in it too. I'd get some art boards, and buy a few samples of black that have a base color that goes better with your vanity and wall tile.

I like your wall paint with your backsplash

I don't like the wall paint with the vanity.

I don't like the rug color with your tub wall tile or vanity.

I think the tub wall tile and the vanity look good.

The backsplash color looks off with the vanity and the wall tile.

I would go lighter. I agree with the person above. Most blacks will pull out other colors when light hits. You may find something darker then what you have but I'm not sure you'll find something quite as dark as the cabinetry.

I love that color above. I think it would work nicely.

A lighter wall for the art would make the art pop much more and definitely go with the lighter option in the bathroom. :)

You need a black brown not a dark Blue