The reality of their relationship

The relationship between Baek-Hyun and Hae-won seemed to be drifting as none of them could summon the courage to talk about what happened that night. 

It got to the point that meals that were always taken together became a two person meal time. Someone was always missing during breakfast and dinner. 

Woo-Bin, who lightly understood where each party stood, did not like this fallen development at all.

Though he had Hae-won all to himself, he wasn't as cheerful as he used to be. And each time he brought up Baek-Hyun, Hae-won would seem a bit anxious and lost.

They weren't kids. They had seen each other naked, they made love together and they shared a bathroom a couple of times so why were they suddenly acting like strangers?

Was Hae-won sad that their trio would reduce to two once Baek-Hyun accepted Lee Ga-Ram? That was the only reasonable explanation. Then, how to fix it?