On July 22, 2014, it was announced she would be making her solo debut under the stage name HA:TFELT. She officially debuted as a solo artist on July 31, 2014 with her first mini album Me?.
Following Sunye's departure from JYP Entertainment and Wonder Girls in December 2014, Yeeun was appointed as the group's new leader.
On January 26, 2017, JYP Entertainment announced that Wonder Girls would be disbanding after she and Sunmi decided not to renew their contracts with the agency.
The group's final single "Draw Me" was released on their tenth anniversary–February 10, 2017.
She was the only member to participate in all of Wonder Girls' activities.
2017–present: New agency, solo career
On April 10th, Amoeba Culture announced that she had signed on with the agency as a solo artist, permanently changing her stage name to HA:TFELT. Her first digital single under the agency, "Meine", was released on October 12th.
On September 20, 2016, local news source Sports Donga reported that she and 2AM's Jeong Jinwoon had been dating for three years. Later that day, the report was confirmed by both agencies.
On April 23, 2017, it was announced the couple had broken up.