Is it normal to be jealous of couples?

I'm jealous of couples too because I've never had a boyfriend because I'm too shy to talk to guys. Once I was with my mother getting lunch in a shop and there was a couple next to us waiting for their order and I saw them kiss and the man ran his hand affectionately down his partner's back and it made me want to spit flames of envy. I'm also jealous of my sisters because they have partners to love them and look after them and I'll never have that. Bloody lucky bitches.