How does one draw the line between obsessiveness and love?

Obsess

verb

To preoccupy or fill the mind of (someone) continually, intrusively, and to a troubling extent.

In love one’s thoughts might be overcome with this person

Their eyes

Their hair

Their gaze

Their laugh

Their way of being

A constant in someone’s mind

Sometimes somewhat intrusively

And troubling

So,

How does one draw the line between obsessiveness and love?