Love is usually defined by "attraction, affection, respect & trust"
to feel attracted to each other happens rather easily
to build affection needs a bit more time
to start respecting each other begins when two people have their first argument
to build up trust takes a lot of time and is a never ending process.....we give some in advance and hope over the years we get to know the person we are together with this trust increases...
Well, at least that is what I believe.