In a lot of cases, a good heart is reflected in the form of good looks, but it can also be deceiving at times. People do have a bit of control on looks if they keep their heart clean from prejudice, jealousy, hatred, ....etc. and all kinds of negative feelings. After all, all children are born beautiful and cute (almost all) it is with time how the negative choices they make in their lives that effect their looks. (to some extent)
I am saying this because you can find people around you who have a jealous look on face whenever they come across a person relatively more privileged in any way. So this does effect their looks. Same goes for people who are depressed all the time and thinking on negative aspects of life, their face lacks freshness. Religious practicing people have "noor" on their face.
It is human nature that no matter how beautiful a person is before marriage, the beauty wouldn't last long (in the eyes of the spouse) unless it is accompanied by good character. Even if a person is not very blessed in terms of look or is not very conscious in making efforts to make his looks attractive, if he only possess a beautiful soul, it would make his looks better (in the eyes of the spouse) with the passage of time.
Physical attraction doesn't play better role than spiritual attraction in keeping a marriage alive for a life time.
You know my Ami used to say exactly what you have mentioned..I used to think what does she know when I was a teenager...but now I understand it wholly.Experience teaches you a lot of lessons:)