"I knew something was missing," Viall wrote in his People blog.
During Monday night's The Bachelor episode, Viall embarked on a one-on-one date with Maltby, a 31-year-old neonatal nurse from Nashville, TN, in Bimini, the closest Bahamian island to the United States. The couple rode bikes, played basketball with local kids and soaked in the culture and cuisine.
"The lovely Danielle. Danielle and I had a great first date and it gave our relationship such a strong start," Viall said. "So heading into this one-on-one I was hoping that we hadn't lost that momentum."
Although Viall viewed Maltby as "a beautiful, kind-hearted" woman with "so many qualities" he's looking for in a partner, the couple's conversation appeared to fall flat in the middle of the date. There were moments of awkward silence and their chemistry seemed off.
"Throughout the day, I couldn't help but feel like we were suddenly missing that spark. Our relationship seemed to lack some of the ease I felt with the other women," the Bachelor explained.
"As our date headed into the night, I knew something had to change for me or I might have to make the terribly hard decision to say goodbye."
Viall was probably dreading letting Maltby go since she has such a tragic past. Her late fiance died from a drug overdose, and she was the one to find him like that. Maltby didn't even know the love of her life at the time had substance-abuse issues, and it took her a while to open up her heart again.
"Danielle has already experienced tremendous heartbreak. I couldn't help but feel that, even though I cared so much for this woman, we were not going to get back to the place we were on our first date," Viall wrote.
"As the evening progressed with the thought of maybe meeting Danielle's family in my mind, I knew... it was time to say goodbye. I knew I just wasn't ready for that next step. I wish nothing but wonderful things for Danielle. She deserves an amazing man and a life full of happiness."
Viall was noticeably upset to send Maltby home -- confessing it was "difficult and heartbreaking" -- and she took the breakup hard, but he also saw it as a step forward in his journey onThe Bachelor.