Don't get me wrong, I'm not saying that the physical stuff should be a big deal in a relationships. What I am saying is that.
1- I don't think it's a good idea ever completely stop trying to impress the person you are in a relationship with. We all like to feel like the person we love values our opinion, and when that person makes it apparent that they aren't trying to be their best for us anymore that's basically saying "I no longer care if you think I'm attractive or not." I knew this girl once who was always complaining that she didn't think her husband found her attractive anymore. One day she brought in an old picture of herself, as she looked when she first met her husband. I swear she looked like fucking Pamela Anderson, thin and pretty with huge boobs and long blonde hair; basically most guys' dream come true. Since then, she had gained a good deal of weight, gotten a breast reduction and cut all of her hair off. I'm not saying that any of those things are necessarily bad, but she looked nothing at all like she did when they met. How could he not see her differently? I just don't think that we should assume that just because someone has promised to stay with us, we should stop doing all of the things that drew them to us in the first place.
2- I think it's very unhealthy to view taking care of our bodies purely as a way of attracting a mate. Our bodies are important. They are the most valuable thing any of us have. We should try to be the best we can for our own benefit just as much as for the other person, if not more so. Our bodies are our own, we should focus on making them what we want them to be, not what we think another person will want them to be. If we pay more attention to our own goals for our bodies not only will we be more motivated to keep it up, relationship or not, but we will also attract people who are interested in who we really are, not just some image we are presenting simply for the purpose of getting their attention.
"Don't you like me anymore?"