Jealousy as if your lover flirts with someone else is sometimes required and natural.We are attached and often are possessive (think that we do possess) about people in our life.But these feelings are only prevalent in initial phase of any relationship.As our bond grows deeper and we understand the true nature of our loved ones, we drop these inhibitions.
Jealousy for your neighbours wealth is a different thing ALTOGETHER. It springs from hatred and not from love as was the case in the former example.
IN short jealousy is a manifestation of feelings of inadequacy with in our selves.I feel jealous for other suitors (potential suitors) of my lover because I feel that I am not good enough!
Further in latter case I feel jealous again out of my limitations to earn more.
IN short jealousy = inadequacy (insecurity) in disguised form.
Life Lessons, Love Hacks 