ak482 , I have one trigger in the sense that I have SAD so I know that at set times of year I will be low but as for why that then trips over into more serious periods of depression...not a clue , it would be nice if I did because it would be easier to tackle and explain so with you on that one.
As far as the issues of sex and intimacy , there is such a pressure on it now , to look a certain way , to be in relationship with a certain person and well you can't just be having sex , you've gotta be having mind blowing sex every time.. totally ridiculous and as well as making people feel awful it sort of devalues the whole thing anyway.
I don't know if you're religious and I'm certainly not but there was a christian nun called Julian of Norwich who wrote a book called revelations of divine love . There are parts of it that are headache inducing but there are parts of it that have really spoken to me in a general way when I've been feeling very unloved and unlovable so maybe it's worth a look.