I liked a guy very much. I even wanted to marry him. I always prayed to God for making him my husband. He is very handsome. I even prayed for his break up. I mean I don't know if he had a girlfriend or not. But I liked him so much that I said "if he has girlfriend he should break up with her". I don't know but for some reason I am not interested in him anymore. I'm going to get married to someone else . I'm guilty for asking his break up although I am unaware of his relationship status. Will Allah accept my apology and forgive me? Or Allah will punish me with a break up with my fiancee?
See the following hadith: Sahih al-Bukhari 216
Narrated Ibn `Abbas: Once the Prophet, while passing through one of the graveyards of Medina or Mecca heard the voices of two persons who were being tortured in their graves. The Prophet (ﷺ) said, "These two persons are being tortured not for a major sin (to avoid)." The Prophet (ﷺ) then added, "Yes! (they are being tortured for a major sin). Indeed, one of them never saved himself from being soiled with his urine while the other used to go about with calumnies (to make enmity between friends). The Prophet (ﷺ) then asked for a green leaf of a date-palm tree, broke it into two pieces and put one on each grave. On being asked why he had done so, he replied, "I hope that their torture might be lessened, till these get dried."
In particular, note that "to make enmity between friends" is a "sin". It's a rather specific and unusual question to ask about the status of this act if one of the two "friends" never existed, but I'm going to guess that it's better to not engage in such wishes. No one can predict the judgement of the Creator, so it's best to ask for forgiveness and avoid the same mistake in the future.