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.