Envious people are lonely people. I truly feel empathy for them. They have very low self esteem and feel that their self worth is almost non existent. They are living their lives with feelings of discontent or resentfulness and are longing aroused by someone else's possessions, qualities. In other words, they see in other people the qualities or things that they themselves are lacking but probably could obtain with the proper efforts if they didn't waste the precious little time that we spend here on earth. Short answer now, yes I would keep a friendship with a person that was envious of me but at the same time I would try to assist them in attaining the thing or things it is/was that they are lacking (baring my spouse of course, she is out of bounds, but someone like her for them if a true committed marital relationship was what they were in search of).