None of us know what is going on in the mind of another individual person so it's impossible to know why this certain individual doesn't respond to you anymore. All I can say is God is in total control of everything so rely on him instead of feeling defeated because someone you liked isn't responding to you anymore. I have experienced two divorces and had two other partners leave me besides. That is what God has given me in my life so far but since I fully trust God and know what the future will be like in the next generation, I don't put my hope in the things of this world anymore. It's going to be destroyed soon anyway.
Then we will never be sad, lonely or frustrated again. Here is God's promise;
Isaiah 65
16: So that he who blesses himself in the land shall bless himself by the God of truth, and he who takes an oath in the land shall swear by the God of truth; because the former troubles are forgotten and are hid from my eyes.
17: "For behold, I create new heavens and a new earth; and the former things shall not be remembered or come into mind.
18: But be glad and rejoice for ever in that which I create; for behold, I create Jerusalem a rejoicing, and her people a joy.
19: I will rejoice in Jerusalem, and be glad in my people; no more shall be heard in it the sound of weeping and the cry of distress.