Answer:
I can be simple or I can be complex. I can be found in this riddle or in everyday life. I can be shapes or even colors.
If you lose me you may cause people around you to lose me too.
A trail, a union, together tied. Come across me and you will find you cannot change the course I'm on. Without me you cannot travel on. What am I?
I fly away as soon as you set me loose. People around you may slowly move away once they sense my presence.
I have a ring but no fingers. I used to stay still all the time but nowadays I follow you around.
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.