What should I do about having hurt the feelings of someone I was deeply attached to, due to my distancing myself from them for the sake of Allah, and does this hurt necessitate sin?

One must avoid and be wary of excessive attachment that is displeasing to Allah, lest it lead to falling into indecencies by following the footsteps of Satan, who commands immorality and wrongdoing. The ruling on forbidden love and admiration has been previously explained. If the avoidance of this forbidden relationship results in harm to the other party, then there is no sin upon the one who avoided it; for every soul earns only for itself, no bearer of burdens shall bear the burden of another, and no one commits a sin except against himself.