what you just described sounds like textbook depression to me. outwardly everything seems fine but inside you feel empty and hollow. and your rational mind cant find any explanation for it.
i was much the same. outwardly everything seemed fine. but inside i didnt see the point of anything. i wasnt getting any joy from anything. my partner, who im madly in love with and is a total angel, was suddenly irritating me beyond measure. in fact everything started to irritate me. i slowly started isolating myself because i didnt see any point to talking to people.
this went on for years. one day i read an article about depression. the person described there symptoms and it basically described my life. suddenly i had an explanation for how i felt.
since then ive been seeing counsellors and taking anti depressants. i still have bad days when i struggle to get out of bed, but things are starting to look up. im beginning to enjoy things again.
your not alone my friend. there are millions of us out there. dont suffer in silence. go to the doctor and tell them how you feel. things can get better