In life, you cannot keep up with every promise you made, every word you gave to the person which gave him hopes that you will show up on your promises, you will fulfill them. Does that mean you should stop making promises? Certainly not.
What we have learn always is, if a person fails to do what he said he will, it means he has changed. And everytime the change has to be adverse and something to do with betrayal. Being on that part of story where you can easily blame or categorize someone is very much simpler because you are not answerable. But being on that part where you have been tagged as ‘changed’ is harder because you know you have not changed and you constantly have to make efforts to prove them wrong but there are more chances of not being convincing to them because people tend to be adamant of refusing their change of mind.
The point is, we are not supposed to please everyone in our life. If people are mature enough and they love you and that love reciprocates, there is never a need of explanation. Explanation of why you didn’t show up. We are humans and we are very bad at empathising someone. We always die for explanation, infact we wait for the other person to be answerable so that we pounce on them for answers.
Not everytime a person who fails to keep his word suggests that he is ignoring you or making excuses. Sometimes its genuine. We all need to be generous enough to understand that priority changes as time changes. Thats perfectly fine because people keep coming into our life and there is always a possibility to be more closer to the new things. There might be a chance that you failed to understand the person. That the new person understood the said person in the way he was supposed to.
Its not important for being the priority, it is important to have that person in your life. You need not constantly meet to examine how good your relationship still is. You just have to believe in each other. That is how it works.