My friends/aquiantances are having with their partners as well as with other people?

my single friends/aquiantances are having casual at least a couple times a week. i'm feeling a bit uncomfortable. i'm very ual, very sensual, but i have a hard time with just having with anyone. i'm also concerned about disease. so many men don't like to wear condoms. huh?! why the craze? please help. only serious answers. txs!