Hospital security guard Ekkachai Tiranarat, 44, and 33-year-old housewife Laksana locked lips for 58 hours, 35 minutes and 58 seconds, smashing last year's Guinness World Record by more than eight hours.
The romance of the clinch may have been marred by competition rules requiring contestants to remain on their feet throughout, slurp food and liquids through a straw and even go to the toilet while continuing to press their lips together.
"They were very exhausted because they did not sleep for two-and-a-half days, they had to stand all the time so they were very weak," Sompron Naksuetrong, vice president of event organiser Ripley's Believe It or Not!, told AFP.
The "kissathon" ended shortly before midnight on Valentine's Day, with the male couple who won last year unable to maintain their smooch, collapsing just two minutes before Ekkachai and Laksana.
The pair won B100,000 cash and two diamond rings.
Organisers said they did not plan to hold another competition next year after three straight years of bettering the record in Thailand and will wait for a challenge in another country.