As I've said above, if you're a confident person, you're not going to get depressed as easy. But still allot of things can cause depression
, drugs, confidence, social life, self esteem, fears, poor diet, stress, lack of excersize, poor sex life..... Goes on and on the list is never ending.
But it really does depend on who you are, e.g. some people are fine with no sex in their life, some people couldnt live without sex and can get very depressed after just a month without it.