Should we talk about our feelings ?

How does a "informal " relationship works. I mean , when you want to have sex someone you know and you like each other , but don't want to think about marriage or meeting their families , just for having fun . I'm 24 years old, and I had a toxic relationship for 3 years and I've been kind of frustrated. I met I a guy and I really like him , but we don't want a serious relationship. I would also like to know what do you think about being jealous in this type of relations ? Thanks for sharing your comments in advance !