The divorce happens, but it happens more than five years down the road.
Eventually, they do wind up getting divorced; whatever they tried before (couples' therapy, a trial separation, what have you) simply was not working.
But it still is short-lived, and just because it's not a first marriage for one half of the couple doesn't mean it's not a first marriage for the other half.
After remarrying each other, they get divorced again.
Alice and Bob go through the motions of the wedding ceremony and a reception, only to have the marriage annulled immediately afterwards, using the wedding only to obtain attention and accolades from friends and family, and/or gifts.
Alice and Bob go to get the marriage license, which reads "practice marriage" on it.
"I promise to love you in good times and in bad, in sickness and in health, for richer or for poorer, for better or for worse, until death do us part, or until I get sick of you in five years, whichever comes first."
Invoked: Bob proposes to Alice, his high school girlfriend, right after graduation.
Alice turns down the proposal, (or accepts it but insists on having a longer engagement) because she doesn't feel that they are ready for marriage.
Alice and Bob quickly begin to have difficulties in their marriage, but are committed enough to not give up and make it work.
Discussed: "I thought marriage was supposed to be forever."
Conversed: "It is, but some people just don't have what it takes. They'd rather just hit the Reset Button than accept the challenges of marriage."