Yes, his self esteem is somwhere between zilch and non-existant, but consider this:
- She took him out of pity when he lost his home.
 
- She is his senior at work, considered a top worker at the office and immensely popular.
 
- He is considered a "well he doesn't screw up too much but should try harder".
 
- (Most important) a woman who get married is expected to quit work and become a housewife.
 
.·. He's feeling he cannot ask that of her, since it would ruin her career and he can't provide for them both.