I understand your problem.
First of all think about this. Having a bf or gf a crime? Have you done any mistake in past? I am not able to understand this thinking of your friends mother. How a person can let another person go just because she has a bf? So don’t think like that. If he is interested in you then definately he will resist in front of his mother. So stop thinking from your heart. He is not innocent. Reason of leaving you must be different. Why you begged him for maintaining relation? You have your own personality and you are not less then any person. So maintain your self respect. If a person not able to give respect to your feelings it means he does not deserve it.
On the other hand you already have two bad experiences. So please don’t be hurry in making new friend. In your age this happened. As a third person I can realise that your new friend is taking advantage of your sad feelings. As he become more caring with you. Most of the boy(not all) like to have a girlfriend. But when time come for commitment then they run away.
Believe me as time passes you will feel good and these negative and sad feelings will go. Why you need any friend. Give sometime to your self. Develop any hobby and enjoy your life in full. Because as your life proceed further lot many responsibility will come to your sholders. You have to maintain too many relationships. So don’t take unnecessary stress and enjoy your precious life.
Let me know your thoughs on this.