First, social media is about connecting to other people. It's about building and strengthening relationships through shared opinions, interests, and friendships. Even when "friends" don't share the same views, this medium is not designed to drive a wedge between them. When you see this occurring, don't participate. You're misusing the medium. Healthy debate where no one gets "unfriended" is fine. Arguing is not. Be considerate though, and try not to post anything that would offend others.
Second, social media is not a place to have a lengthy discussion about a controversial topic or when your feelings have been hurt. It's not a place to write announcements about how you've been mistreated. It's also not a place to stalk, trash, threaten, and embarrass another person. Since most of the posts on social media are written, a meaningful conversation can get lost in the back and forth. As one person writes their opinion, then they have to wait until the other person(s) responds. That could be right away or hours and even days later. The delay takes away from the momentum of a worthy dialogue. Social media and written comments should never replace face-to-face interaction when it's needed.
And third, too many other people can get involved in your conversation. If it's a personal matter between two people but it's out there for the whole world to see, then opportunists and opinionated folks can intrude on the conversation and make matters worse. (Some people thrive on mess!)
Social media is all communications. Whether written or spoken in a video, you are inviting people to connect with you. Do so with grace, self-control, and respect. Only then can you get the full benefits of the "social" in social media.