He has to make a decision. When Elsa is followed by Anna, he glances; compares the two. Who is worth more? Because Elsa's family, they're pretty rich. Pretty well-off (but she never accepted their money anyway). Anna is a struggling med student who has fallen asleep during coitus several times, but damn, at least she's there.
She's younger than Elsa. Bigger breasts and definitely more fun in bed.
It's almost too easy to put on that frown of guilt – sadness? – and move towards Anna.
"I'm sorry, Elsa," he says. "I'm so sorry."