When is it the time to take that "WALK"?

I was having sushi in one of the best sushi bars in Singapore the other day. For me, sushi is not a food but a ritual and an art work; it has this special air of care and attention around it. I was sitting in the middle with a friend. At the the opposite corner of this sushi bar, there were few "whites", as we call them in Singapore. A young woman was sitting in the corner, a young man beside her and another man adjacent to him, few more joined later, but by that time I had stopped bothering about them, so I don't exactly remember who they were.
I could tell, like any other woman can tell, that the man, in the middle, kept on looking, or better say checking, at the direction we were sitting. At first I thought, he is curious and puzzled! An over dressed up latino looking woman with an extremely casual eastern looking man in a sushi bar! But the looks persisted to a point that they made me uncomfortable, especially as the girl sitting beside him kept on touching his hands and arms. I told about this to my friend, he looked at their direction and said, "look  at the manner in which his back is towards the girl and his face is towards his friends." He was absolutely right! I hadn't noticed it. The girl must be feeling left out and sad, if not miserable.
At that moment I thought, what would I do if someone treated me like that? Would I have the courage to just walk out of the door? Would I stay and fight back to get the attention I deserve? Would I keep calm, enjoy the meal and keep myself busy with my mobile? Would I tolerate it all with the hope of taking revenge in due time?
Its's sad to confess that I don't really know what I would have done in that situation, because our mental and emotional status can vary significantly from time to time, and we will behave differently depending on them. But I know one thing for sure: before I and that man get to do anything together again, I will first check out the exit ways. I will make sure there are ample ways to walk out of the situations, places, moments, and even next level relationship states! From that point onwards, it is about protecting me from being hurt, rather than looking forward to having joyful time together with that man. I will properly keep going, but not for a long time.

It was March 2013, New year celebration. I went out with this man I was seeing at that time. It was an excellent party, nothing major happened, but the man kept on dancing with this doll face girl. She was pretty and was dancing elegantly. Later that night we went to his place and he started to show me the photos he had taken that night. None from me! And few from that girl. That was my moment to take that "WALK"! But I didn't take it! I thought, I have spent more than a year for this relation. We had remained friends for a long time, then we decided to go on dating. All steps were taken cautiously, and he was a respectable person after all. I thought, I shouldn't easily let go of it! But then my heart would not listen to my rational brain. I kept seeing him for another painful three months! And then it happened again. This time I grabbed my bag, looked straight into his eye and said, "I don't want to see you again." He didn't ask why and I didn't feel the need to explain myself.
I still think, how I wish I had the guts to take that "WALK" out of the door when I felt like doing it the first time!