Wyatt, following Serena Sullivan's instructions, sent someone to investigate Wendy Monroe's brother's matters. He didn't leave himself and stayed at Serena Sullivan's studio, waiting for her to get off work.
Serena Sullivan is a workaholic. Once she immerses herself in designing drafts, she forgets the time.
In this aspect, she is very similar to Simon Sterling.
Usually, Ethan Grant arrives promptly to ensure Serena Sullivan finishes work on time. Today, Ethan had a very important meeting. He called Wyatt, and Wyatt came to look after things.
If Wyatt is unavailable, then it's either Claire Sullivan or First Mrs. Sterling.
Everyone is concerned about Serena Sullivan's health and doesn't want her to be too exhausted.
Money is not a shortage for The Sterling Family, neither for Claire Sullivan, nor for Ethan Grant, and in other words, not for Serena Sullivan either.
She's working so hard entirely out of habit.
