This is where oxytocin becomes important. The warm, fuzzy, affectionate aspect of love, and bonds that last, have to do with oxytocin. Successful, long term partnerships thrive on it when coupled with regular expressions of affection.
However, the human race might disappear if not for the appeal factor of dopamine. More mature levels of love start with the dopamine high of romance and anticipation, causing us to crave a particular person’s presence; and so life goes on.