When do you stop loving someone?

I was once asked this question, why do you continue loving someone who has not shown any response at all? you mean my children? I have no problem with that after all they are my children and as a parent it is my job to love them regardless right? But I could see she was not refering to my children.Why do you do the things that you do,when you know nothing good will come out of it? So I said well I just can't help it . It is my nature to love her(as I have already guessed she was hinting at my god daughter) wheather she response or not. when I choose to love it was not with the hope of getting something in return or a response. If you do something for someone and hope to for something for return then I guess it is not a true love or agape love as the Bible puts it. When God choose to love us it was unconditional. He loves us inspite of our rebelious nature and knowingly some will reject his love, yet he choose to love.Since today is easter day,I thought I will reflect on God's love.
1 Corinthians 13 :4-7 talks about what love should be:-
4Love is patient, love is kind. It does not envy, it does not boast, it is not proud. 5It is not rude, it is not self-seeking, it is not easily angered, it keeps no record of wrongs. 6Love does not delight in evil but rejoices with the truth. 7It always protects, always trusts, always hopes, always perseveres.
To that person who might not understand it at all, and to be honest I too at times do wonder why do I do it. But one thing I am sure of I enjoyed every moments when I am with her and that is good enough for me. I guess in the same way God must be feeling the same when ever we spent time with Him.