When it comes to love and lust, disappointment can be a factor. However, there is more disappointment I find that comes from lust especially when there is lust one way and love coming from the other way. When I talk about disappointment, I am not talking about outside factors but what is between the two people. Disappointments are a part of life, but should not be a part of a relationship. This means you may at times feel disappointed by something that your partner does, but if there is true love between the two people, then the partner will try to change and grow, which makes the disappointment lessened and go away. This is what love does. It cures disappointment. Even if you have disappointment at work or with other outside factors. When you come to your loved one, the disappointment tends to feel lessened or disappears altogether.
However, lust does not help a person with disappointments in life. Lust will give a person a moment of fun and not thinking about the disappointment, yet once the lust is gone, the disappointment is back. Lust tends to work more like a drug, it is fun at the moment but does not help or change anything. So once you return to your life, it does not enhance your life and therefore you return to any issues or disappointments that you had. As for love helps you change and grow, which allows us to help each other to move past our disappointments. True love cannot dwell in disappointments but stays in joy.