Sometimes they fall in love in such a scenario and other times they don't. Can't generalize.
For some......they really do fall in love with their partner after getting to know him/her
For some.....they may not feel that passionate love.......but they accept their fate/kismat.......and that motivates them to develop consideration/tolerance/respect/some form of love for their partner.
And as mentioned earlier.....there are still some......who weren't in love from the get go........and don't fall in love later on either.
good analysis