Tyler had been waiting for Nassar to expose his true intentions.
This wait had already lasted for two days.
As soon as Nassar returned to Sunny Town, Tyler had detected his insincerity through mind-reading.
At the time, Nassar was extremely displeased after being tactfully rejected by Emilia. Yet, he maintained a gentlemanly facade with a smile, which immediately caught Tyler's attention.
<Click paragraph comment to see quote from Chapter 105: Forethought>
Considering Nassar's good reputation among the people of Sunny Town, Tyler immediately deduced that he was the sly, two-faced type.
Usually, people don't hide their true nature without a reason. Since Nassar had been so dedicated to his disguise for so many years, he must be plotting something sinister.
Tonight, Tyler didn't tail Emilia. Instead, he donned a black cloak to cover his face and followed Nassar throughout the night.