Alternative form of ドヤ顔.

success / success in life, achievement in the world

succeed / be successful in life

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend

face / expression

a person's face / a person's reputation

look; face; expression / color

behind, after