As you probably know, metaphors are comparisons of two otherwise dissimilar things, without using a connective word such as “like” or “as.”
Based on your descriptions, you are looking for metaphors that express the ideas of jealousy (for the green bird) and love (for the red bird). Now, it would not be ethical of me to write your metaphor for you, because that’s part of what you should be writing as your own original work. But I can tell you that the way I’d approach this problem is to think about what jealousy and love involve, and then come up with a comparison that expresses that idea.
For example, suppose I wanted to create a metaphor that expressed the idea of bitterness. First I’d think of what bitterness involves. Bitterness creates a feeling of negative emotion, in which it is difficult to have positive, healthy feelings. So, I’d try to think of something concrete that expresses that idea. I could say something like: My heart now beats in the dry, cracked earth of my bitterness. In this way, I am comparing my emotional state to dry earth in which nothing can grow and live.