Have you heard the quote "watch what they do... not what they say"? Wise words.
People say any amount of things, but do they mean what they say? How many people actually say what they mean and mean what they say?
The truth is, people will say what they think you want to hear. In order to keep the peace, or to avoid dealing with anything, it is easier to placate.
You will find that you cannot trust what people say all the time. When someone tells you something, then reneges on that statement, it should be harder to believe the next time. Your "gut" will tell you that this is not true, don't believe it, and yet sometimes, your mind wants you to go along with it. We have gotten used to "hushing" our gut when we get a message that we don't want to hear. This, as everything, is about you. The person you are dealing with may be the one lying, but you are choosing to accept it. We will always hear exactly what we want, and if we are not ready to hear it, we won't.
Some people have such huge walls built to keep the emotions at bay, but if you pay attention to their actions, you can see who they are. They cannot hide, there are "tells" with everyone. So if someone is saying yes to you and their actions are saying the opposite, it may be time to consider if it is good for you to continue to listen. You may just have to walk away. The only one that you can change is you. It is not your job to try and fix anyone, you can only fix yourself. We don't like to think that someone would lie to us, or that they didn't love us after all; but no matter what your age, do you want to wake up in twenty years still accepting less than you deserve, being unhappy and unfulfilled. Only you can put an end to what no longer serves you.
Do not accept a YES from someone that doesn't have the right to give you a NO in the first place.