Cutoff line between Friend and love

The other day, I ate out with my collegues. My one of collegues brought a topic up.
She is wondering about her and her boyfriend. She thinks their relationship is like just good friends. Because they can share everything , they don't need to bear anything.
For example, when they walked on the street and she finds good-looking guy and say to him "He is a cool". Normally, it's offensive to him because she is into another man. However, he agrees to her opinion. So, she thinks about lover and friends. They have been having good relationship but he is never jealous for her opinion. She feels whethere he loves me or not.
I listened to her talk and I think he just wants to shere anything with her and there is no boundary between her and her boyfriend. I think that's great.
But Love is difficult with a captal "D".