Why are people so...?

It is sad. When you go out into the real world you will find a lot of people are like this and actually do things like this. Im not religious or had a tough upbringing but it does annoy me that people are so loose on morals and do these things. I am starting to loose faith in people, partly cause I had an experience where I was cheated on. I really wish people would only go after others who they want to be with long term or atleast be honest with them :/