a piece of paper
The gf isnt gonna take all your sh*t when you leave
The commitment you made to her when you married her. That's the only difference.
Wife you need buy her a wedding ring.....no need for girfriend.
priority and responsibilities
She has a ring on her finger and she is a hell of a lot more expensive.
When you're dating a girl, you wonder if she'll stay. When you're married, you wonder if she'll leave.