There are various ways the pain behind seeing what others have and wanting it for yourself arises:
You just hopelessly want what they have, you don’t know why you want it but you just do.
You know deep within for whatever reason that you can never have it.
You know that you could have had it, had things at one point in life gone differently but now that you are on the path where you are hoping things had happened differently, you know you can never go back in time and hop on the path leading to what you want.
You know you have the ability to get it but you just don’t know how or what you have to do to get it.
The most painful of them all you ask me?
The last one. Being helpless, not knowing what you could differently or not knowing what you are doing wrong or just not knowing where to begin is torturous!