I would say the cause is that current internet social connection techniques don't have enough depth to them. Telephone doesn't let you see hand or facial emotions of the other person. Twitter/facebook is only using a keyboard + reading text. Instagram you can see a snapshot of an instant and peoples thoughts about that instant. etc...

VR is working to try and bridge all of these by essentially creating a transporter/teleporter to a shared physical space. Imagine if VRChat was a 1-to-1 replication of you. I feel like this is one of the end goals of VR.

  Its easier to connect and find similar people through internet so i get why it is like this, but i think its also the factor thats making us less mentally balanced

This isn't true of just internet, this is true of cities. People no longer care about one another, each person/bond is replaceable with another one. i.e dating apps only help prove this fact. We no longer need to rely on one another to survive and therefore are more independent. We are less willing to give up (sacrifice) parts of our independence and less tolerant of flaws in others. I think this is what leads to higher divorce rates now. How many people live in high rise buildings and actually know many of their neighbors?