If you have an out look like this you will never be in a healthy relationship. If you are afraid someone will cheat on you, or if you are with someone who goes and sleeps with someone else because you had a big argument, it is not social media that is the problem. It's your relationship.
Before social media, there have always been bars and nightclubs to pick someone up. If your relationship is healthy the other person will not go out and sleep with someone else because you pissed them off. When someone cheats on you it's because they don't respect you, or you are dating/married to someone who is not emotionally healthy...it has nothing to do with social media. Trust is the foundation of any healthy relationship.