In our life we meet various people and to be honest in which mostly people come and go like seasons. And whenever they left they teach us several lessons.
At some point of life, some of us regret being good to people specially on those who left us because they never appreciate our efforts and it's feel like we wasted ourselves for them.
But I want to say that our goodness always lead us to better outcomes in our life and we should never regret for being good to others. We need to understand that its our positive quality and its necessary for the humanity and the most important thing is that we're playing our part in it.
I must say when we are good to others but they still left us and never appreciate us it means they're not the right person for us even if it's our friend.
In fact those who leave good people always regret on themselves for leaving us and for not appreciating us but you know what, everything have it's own time and even for appreciating someone or something have it's own time otherwise people can only regret...
Remember that our goodness never waste and it comes back to us through different people or different reason. So never regret on yourself for being good to others.