That bit about not being hungry was a lie, but she wouldn't tell him that. She needs the hot, steamy water and fluffy bubbles to relax, calm down and get her head back.
She strips off her clothes and stands before the mirror for a minute, looking at herself. She thinks she looks tired. She is tired. Lonely.
Turning from the mirror she steps in and sinks herself down in the tub, immediately feeling the stress melt away.