Cheating?

Idk where else to post this but if any of you gamers could help me out, that would be splendid. I don’t know anything about the ps4 at all.. I was just wondering are there ways your spouse be on there interacting with people outside of the game? Like I’m pretty sure it’s not hard to add other people to play with and exchange numbers etc.. can someone verify this with me? I just don’t know if I can even trust my partner on the game system. Yes I have trust issues..