"I finally felt like I was starting to understand her and that our relationship took a giant leap forward," Arie wrote in his People blog.
Arie admitted there was "so much anticipation" going into his first solo date with Lauren in Paris, because as viewers saw, Arie was incredibly attracted to the 25-year-old technology salesperson from Dallas, TX.
"Lauren was still a bit of a mystery to me. I really liked her but had no idea if those feelings were mutual. Being the Bachelor doesn't necessarily mean that the women are into me, and one of my biggest fears going into this was falling for someone who did not reciprocate those feelings," Arie explained.
When Arie and Lauren took off on the Seine River by motorboat, she told the Bachelor she was very "anxious."
"It eased my nerves to know we were feeling the same thing. Walking through Paris was a really incredible first date. We snapped Polaroids in front of the Notre-Dame de Paris, tried foie gras in a market, and fed pigeons while they landed on us," Arie revealed.
"Another fun moment you missed was a street artist drawing our portrait (I think we definitely overpaid). During the day, I was still unsure of where I stood with Lauren. All I wanted was for her to open up and connect with me, and it wasn't happening. Though the date was fun, I wondered if the public nature of a walking tour made it hard for her to open up."
When Arie arrived for dinner at Le Grand Vefour, one of the oldest and most historic restaurants in the city, he had questions and concerns about his relationship with Lauren given she was so quiet, guarded and reserved that day.
"I realized there was still so much pressure going into the evening. I still had so much interest in Lauren, but if she didn't have interest in me, I knew I couldn't give her a rose," Arie said.
"At this stage in the game, getting a rose really means that I see potential for you to be my future wife. I saw so much potential with Lauren, but I feared running out of time. Being vulnerable so quickly is difficult for some people, but one thing we didn't have the luxury of was lots and lots of time to ease into things."
Because Lauren was uncomfortable on-camera, Arie took it upon himself to open up about a very personal story. He shared that his ex-girlfriend had suffered a miscarriage and broke up with him when he was out of town for racing.
"When I first started on this show, I honestly didn't know if I was going to talk about one of the darkest periods of my life," Arie confessed in his blog.
"But, after wanting Lauren to trust me and be vulnerable for so long, I knew I needed to be the same with her. This journey wasn't all about the women opening up to me and telling me about their pasts, I had to do the same in order to build a relationship that was strong and real."
Arie then learned at dinner that Lauren had trouble being vulnerable because she was afraid to trust a man, mainly due to the demise of her parents' marriage and a recent failed engagement. She did receive a rose at the end of the night.