Every once in a while, Farrah Abraham is willing to show her softer side.

Yesterday, the Teen Mom OG star and her daughter, Sophia, visited the gravesite of Farrah’s high school boyfriend, and Sophia’s father, Derek Underwood — who the mother and daughter duo affectionately call “Daddy Derek” — and celebrated what would’ve been his 27th birthday. Tragically, Derek died in a car accident before Sophia was born; he was 18 when he died.

“Happy birthday Daddy Derek! We all love you so much,” Farrah captioned the sweet pic. “Thank you for always watching over us.”

MUST SEE: Farrah Abraham to Kailyn Lowry — “Stop Getting Knocked up by Randoms!”

Derek’s death has always been hard on Farrah and her daughter, 8; during one particularly emotional episode of Teen Mom OG, Soph declared that she “wanted to die” so she could be with the father she never met.

“When you say you want to die to see him, it really makes mommy sad,” Farrah told her daughter. “Do you know that it hurts mommy when you say those things because I care about you, and I love you?”

Since skyrocketing to fame on Teen Mom, Farrah has shared how she intends to honor Derek’s memory with her daughter.

MORE: Check out Farrah’s Controversial MTV Movie and TV Awards Look!

“Every year, we go to Derek’s gravesite,” she previously said. “We take pictures, we record it, and I have a whole baby book for Sophia with letters and pictures telling how and why things happened, and why I’m here today alone.”

Scroll through the gallery to see some rarely seen shots of Farrah and Derek.