Loss of control, miscellaneous challenges, relationship friction, increased pressure and ticking clocks

A flight being delayed
The character's child getting sick and needing care
Bad weather forcing the character to postpone vacation plans
Learning that a parent has had a heart attack
Someone with whom the character has plans calling to cancel 
Finding a stray animal on the roadside and needing to care for it
Going for a run and finding someone who has collapsed on the sidewalk
The character leaving for an anticipated date and discovering their car battery is dead
Construction causing a detour during a road trip 
The character becoming ill while traveling
Witnessing a crime while going to meet a friend and having to report it and talk to the police
Getting injured at work and needing to go to the hospital
Going into labor prematurely
A routine doctor's visit resulting in emergency surgery
A merger at work changing the character's responsibilities or doing away with their position
A retiree being scammed out of their nest egg and having to go back to work
An unexpected divorce changing the trajectory of the character's future

Missing an important meeting or appointment
Not having certain items that would help navigate the change of plans (access to a digital calendar, contact information for someone, a cell phone charger or spare change of clothing)
The delay causing other people to wait on the character
Having to reschedule 
Missing a meal
Having to renege on a promise
Apologizing for not being able to follow through
The change causing tension with loved ones who are also inconvenienced
Having to fill out paperwork, file reports, or talk to officials
Appearing frazzled or disheveled to others
The character taking their frustration out on others and causing a scene
The character panicking and saying or doing something they later regret
Losing money in the form of non-refundable deposits
Having to give bad news (about a canceled trip, etc.) to children