should i feel jealous of others who have relationships, when i don't have anybody

[c=003BB2][i]i'm a man who has had mental problems my entire adult life and because of that i never found a partner or relationships...i have lived alone 18 years now in a little apartment...and when i see someone happy with relationships and people in their lives, i feel jealous, bitter and annoyed.. because i think that should be me.....why do i have to endure a lonely life?

how can i not feel like that?[/i][/c]