He loves you I guess and he wants to see how you react if another girl stole his heart. He just wants to see if you love him much to the extend that you cannot support another girl next to him.

Because boys play with girl's emotions

R you serious about this question? The answer is because he laves you. You should be happy about it by the way because jealousy is great and if their he does not get jealous that means he doesn't love you.

White is cute I guess