Becca, 31, captioned the slideshow, "Should I start following him on the gram yet or what?"
While most of Becca's followers seemed thrilled for the Season 14 The Bachelorette star and showed support for her romance with the 29-year-old real estate broker, one troll slammed Becca pretty harshly.
"The reason so many dudes don't fully commit to [Becca] is because she freely gives it up every day," the person wrote, along with a face-with-tears-of-joy emoji.
Many of Becca's followers lashed out with replies such as, "Get off your keyboard and get a life," as well as "unfollow her if you have a problem."
"This person sounds like they hate joy," another Instagram user wrote.
But Becca stood up for herself and responded, "Lol. How is your relationship going?"
When a fan commented on Becca's September 8 post about how Thomas had "red flags" written all over him, Becca replied, "Red is my favorite color."
On Bachelor in Paradise's Season 7 finale, Becca was shown breaking up with Thomas and crushing his heart before overnight Fantasy Suite dates because, despite having "an incredible start" to a relationship, Becca didn't want to leave The Bachelor franchise for the third time with a man unless she knew everything about him, including how he'd face adversity and real-life challenges.
However, the finale concluded with an update on Becca and Thomas' relationship, revealing they had reunited after filming ended and are now dating, "happy and in love."
During a joint appearance on a recent episode of the "Talking It Out" podcast hosted by The Bachelorette alums Mike Johnson and Bryan Abasolo, Becca revealed she's the one who tracked down Thomas' phone number and initiated their reunion.
"I was mad, I was hurt... but knowing how I felt about Becca and I knew she felt it too, I had faith it was going to lead to a future conversation, and I was just waiting for the moment and opportunity to see her again," Thomas admitted of their Paradise breakup.
"When she first texted me, she started off, 'I know I'm probably the last person you want to hear from right now.' And it couldn't be further from the truth, that's the one text I was waiting to hear."
Thomas shared, "That's the one person I wanted to see. That's the one person I wanted to hold... [Our split] showed us that we experienced something and it was taken away from us for a moment."
Becca said they picked up right where they left off and her relationship with Thomas is different from ones in the past because he's so passionate about their relationship and was prepared to fight for her "tooth and nail."
"He is so supportive and he's just funny and quirky in the cutest ways. Everything about him, I just felt safe with, unlike anything I had in the past. I was just like, 'This guy is my guy,'" Becca gushed.
Prior to starring on The Bachelorette, Becca had been engaged two times.
She had her heart broken by Arie Luyendyk Jr. on The Bachelor's 22nd season in 2018, when he decided he was still in love with his runner-up, Lauren Burnham, who is now his wife and the mother of his three children.
"I'm gonna probably hate myself for actually admitting this to anyone, but I called my mom -- and even though I was engaged twice in the past -- I was like, 'Mom, I think I want to marry this guy,'" Becca said on the "Talking It Out" podcast.
"It's the first time I've ever actually said that out loud."
Becca also revealed Thomas has sent her "multiple text messages" asking about engagement rings.
"It's something we've talked about," Thomas disclosed. "I mean, I don't want to spend my life with anybody else... I wouldn't want to wake up next to anybody else."