This will upset many people I'm sure, but son beware people who dress all in black. Especially don't enter into relationships with women who wear all black.
Life will go so much better for you if you choose your friends and lovers instead of accepting whatever pops up. In particular, we'll talk another time about how the girlfriends that have to be worked for tend to be better than the ones that come easy. So be a little objective about people who come into your life, and then be a little selective.
Clothing sends a loud and clear message about people's perception of themselves - how they choose to colour themselves. I am firmly of the belief that most, if not all, people who choose to dress all in black are trying to erase themselves. They suffer from some form of low self esteem and/or depression. This kind of person may well be a great collaborator in business or art, or not. But they could be dodgy friends and they will almost certainly be a bad choice for someone to spend your emotional time with.
There are other "disfunctional" fashion choices that may or may not be sending us a warning message when choosing life partners, such as "shouting" colours or all-drab-brown, but nothing is as reliable an indicator that something is seriously wrong as universal black.
The only exception I can think of is the LBD - Little Black Dress. This is a classic fashion choice for a formal occasion but most women will choose to accessorise it with some colour.
...and I'm overlooking the obvious scenario where she's wearing next to nothing and it's black :)
But if all her choices are black then read the signs.
The obvious example where this does apply is of course the goth-girl. If you can't see that people who choose to look this way are seriously screwed then you are in for a rough ride.