Unfortunately they do. What usually happens is what I call the "relax" or "Mission Accomplished" scenario. After someone has gotten married they often (stop) doing the things that won the heart of their mate!
Many began to take their spouse for granted, become less considerate, and less affectionate under the guise that marriage means he or she is not going anywhere. Initially their mate may go with the flow or attempt to go along to get along. This leads to tension and stress build up. It's not uncommon to hear someone say, "He or She is not the same person I fell in love with."
When you think about it that's kind of a ridiculous way to think. Just because you got the job doesn't mean others stop sending in their resumes. With a divorce rate at 50% and infidelity on the rise it's clear that no one is "stuck" with anyone. It's important to remember everyone has "options" and marriage is an "at will contract." One should never stop trying to impress their spouse!
Awhile back I expressed my take on commitment with the following hub.
Marriage is a garden which has to be nurtured or it will die. As the old saying goes, "The same thing it took to get your baby is the same thing it's going to take to keep them."
The wedding is just one day. Marriage is a marathon for life. There is no finish line.