Obsessed with the color black - am I depressed?

I don't think you're depressed it just seems like you're in a gloomy stage, after a 3 year relationship I think anyone would be. You become sad because everything reminds you of her, and that's normal. I'm sure it'll pass, but if it doesn't then I would seek medical help. Just try to think positive, go on dates, you need to live your life because time is not waiting for you and while she may be out having fun your upset that the sun came out. Good Luck!