Then he walks off in a tuxedo and saves his species.
This part kills me. It's a nice little detail that brings Odo full-circle. He spent his whole life frustrated at having to take a certain shape just to please other people. Then he finally accepts himself and starts to explore who he really is and all the things he can be, and finds someone who loves him in his natural form. And the last thing he does before he leaves is to go out of his way to take the form he thinks she would like best. Gets me every time.