Police believe the suspect called in the threat to interrupt the flight being taken by his ex-girlfriend, which was due to depart at 5:30 a.m., said Sea-Tac Airport spokesman Perry Cooper.
Out of an abundance of caution, all passengers were removed from Southwest Airlines Flight 149. After the 166 passengers were rescreened and the plane was searched, nothing suspicious was found.
The plane was given the all-clear and rescheduled for takeoff about two hours later than originally planned.
No other operations at Sea-Tac Airport were affected by the situation.
After the plane was reboarded, Port of Seattle police investigators were able to identify the suspect and arrest him at his Lake City home.
The suspect will be booked into the King County Jail on suspicion of making a bomb threat and domestic violence threats to harm, Cooper said.