What is this je ne se quoi?

[Anonymous]

I'm trying to describe this girl, but she has these multiple personalities. So I'm trying to describe to each one what I think of her, but I keep coming to the roadblock of "She is" but don't know what comes next. I don't know the word and I don't know how to describe the word. What does this mean? I'm fond of her but not in love with her. She and I get along so well, and I will tear apart anyone limb by limb who hurts her. That's enough of my tangent though... What does this mean?

[KDA20]

Je ne sais quoi sums it up perfectly - My feeling is that maybe your idea of love is fireworks and butterflies in the stomach. Sometimes your ideal match is the person you are most comfortable with, could even be your best female friend. Who knows I am only guessing. You alone know what is in your heart.

[Anonymous]

A certain something that's indescribable