Once you start dating and get involved with people, you realize that some of them just aren’t relationship material. They just aren’t built for monogamy. It has nothing to do with you, it’s more of a social construct.
Be free, do what you want, and who you want – and always try your best to avoid the consequences of hurting someone’s feelings. It took me a while to figure out that most people just don’t care about you.
I know that no one is perfect, but give it a rest people. You don’t have to be a jerk in order to date someone. Be honest with them – put your cards on the table and if they agree, great. If they don’t just move on.