You met someone you instantly connected with on so many levels, and you are talking almost all day, and it seems great because this time the interest seems to reciprocated and they actually want to talk to you. They make sure to text you good morning and do not go to bed before saying good night, and you think that you have finally met a person who can give you the attention you want, so you make sure to shower them with attention as well.
When a child receives a new toy, they make sure to play with it almost all day during the first few days, but then their excitement fades away as they begin to discover the limitations of the toy and lose interest. They then start playing with it less frequently, once a week then once a month, once a year, until they have outgrown the toy and stop playing with it. Human relationships are similar and I have experienced it several times, so I no longer expect anything to last just because the first few days have gone well. We barely know anything about it other which makes it all exciting, but once imperfections begin to show, we begin to find defect in our toys and set them aside looking for a new toy whose defects are hidden to us. After all, we cannot be harmed by what we do not know.
They no longer reach out, so we begin to reach out. They constantly say they are busy, but they have forgotten that we have met them during the busiest time of their life and they still gave us more time then they do now. We all have the time in the day, but we have priorities. We all send good morning texts, but we choose either to include or exclude people from our "must say good morning to this person" list. If they have stopped making time for you, just leave it at that. There is nothing you can do, for you have just gone down on their priorities list and they have a reason for that; whether you know of it or not, or whether they will admit to it or not.
When this happens, do not force yourself back into their lives, for you have a life of your own to live. If you have not already experienced spending time with a person who is more interested in texting other people than talking to you whilst you are sitting in front of them, it will feel the same when you are trying to speak to this person who no longer initiates conversation with you. Forced relationships and friendships are the worst because you will not be satisfied and they will constantly try to brush you off which will only hurt you. Save face and leave people who do not walk away from you.