Earlier this week, some photos of Seohyun at a wedding started going around online.
In one of the photos, Seohyun is smiling next to Hwan-hee and making a heart with her.
The other photo is of Seohyun reading a letter during the wedding ceremony to Hwan-hee and her husband.
Hwan-hee, who made debut as a solo artist, was one of the trainees most likely to make debut as a member of Girls' Generation.
She is said to have failed in the very last round of SM Entertainment's competitive selection process.
Previously, Hwan-hee was spotted at Girls' Generation's concert as well.