If someone does not loves you, chances of changing that to genuine love is really slim. Honestly, if you somehow manage to marry that person s/he may accept you as spouse and live as a spouse but when it comes to love it is a spontaneous feeling, that no one can control, not even the person who loves.
Sometimes walking away from someone after letting that person clearly know that you love him or her and thereafter being refused may make that person realize that s/he too actually loves you. But dancing around someone or begging rarely changes hearts for better.
There are always other people in this world, who may love you, in the end it is smarter decision to get involved with someone who loves you, you can always try to reciprocate. But when it is the other way round you can’t force the other person to reciprocate, respect your love.
In the former case the cards are in your hands, you can make or break the relationship.