In the beginning it's usually about infatuation, attraction, romance, having fun, laughter, and chemistry.
Note: Most (new) relationships start off with a "natural high".
Both people bend over backwards to impress the object of their affection, avoid doing anything that might blow their chances of being with them, rarely if ever use the word "no", make one another's happiness their top priority, talk and laugh for hours, exchange cards, token gifts, and plan spontaneous getaways "just because" are all part of the "infatuation phase".
It's not until they uncover their differences after a few disagreements or misunderstandings that they're in a position to determine if they're "in love" with the person or the fantasy.
Over time people learn if they share the same values, want the same things for the relationship, naturally agree on how to obtain those things, and last but not least have a mutual depth of love and desire for one another then love can last.
Compatibility trumps compromise!
Like attracts like and opposites attract divorce attorneys!