It is my personal opinion that a lot of relationship start to go down the drain because people forget to show appreciation. For some reason, it seems to be hard for men to be romantic... either because it is not manly, they don't know how, or because they just don't realize it's importance. A lot of men don't realize that it's usually not how much money they spend, but what they do to show you they love you. A single rose... a handwritten note saying "I love you!"... taking the time to say "you look beautiful" when you look your worst. Simple things like that are what women need to feel loved and appreciated.
In my experience, you truly have to learn to communicate with the man you love to let him know what makes you feel good about yourself and your relationship because most men are clueless. Men are also not good at picking up subtle hints or reverse phychology. Most men will learn and realize how easy it is to keep their women happy if you show/tell them how. On the other hand, some men are just too stubborn and selfish. The thing is, I believe that women deserve these things.
So if you want these things to happen then I suggest gently bringing it up at a time when you are alone together, when you are both at ease and in a non stressful situation. You want him to see that this would be a good thing that would make you happy so you don't want to make the discussion confrontational. Once you get them to do it... give LOTS of praise and make it abundantly clear how much you appreciate it and that you would love to experience that more often. You may have to remind them again. For some reason, men are notorious for slacking and forgetting about these kinds of things, but it does get better!
Also, if it's bringing you down and you don't feel appreciated, then it's time for a change. He needs to know how you feel. If you keep things bottled up, it will make things worse for both of you and he will never understand why you are unhappy. Just my personal opinion.