A lot of the times 1st couple tends to be more on the wholesome, healthy side. Things like coworkers, roommates, friends to lovers, etc.
Meanwhile 2nd couple have a complicated dynamics. not always but a lot of the time it includes re encounters after a messy past or they face more difficulties bc of their backgrounds
In short authors usually try more complex characters after, when they already have a successful couple

why is it that most people tend to love the side couples or second couples a lot more than the main/previous couple? ive been wondering this because i always find myself gravitating towards the side characters as opposed to the main ones in most things i read
do they just tend to have better dynamics or something? what makes side couples click better than the main for you guys