Abigail posted a video montage of the couple first and wrote, "I love you @noah_erb."
The 26-year-old Oregon native captured sweet and playful moments with Noah once they reunited after their stint on Bachelor in Paradise in Mexico.
Abigail and the 26-year-old travel nurse apparently enjoyed many secret hangout sessions while trying not to spoil the fact they got back together after breaking up on Season 7.
Abigail and Noah hiked in the woods, climbed rocks, kissed under a waterfall, soaked up the sun poolside, shot-gunned beers and rode bikes together.
The pair showed off their chemistry and connection, and a running theme in the video was Abigail laughing and giggling at her boyfriend in the background.
Meanwhile, Noah gushed on his Instagram Stories that Abigail is "the love story" he didn't know he needed and is "thankful for."
"It's a shame y'all only get to see a tiny bit of our lives, but believe me when I say we make the most of it," he wrote, adding how he and Abigail had been sneaking around for four months and he's so happy to finally declare her "babes" in public.
On Wednesday, Noah also uploaded a sweet video of the couple to his Instagram account and gushed about his happy relationship.
"I love you @abigail_heringer. Here is to laughing through life until we are old. (World, meet my new GF, turns out we do know how to talk to each other and I think I'll keep her)."
Abigail and Noah didn't exactly glide through Paradise as a couple. They briefly split along the way due to Abigail missing a spark with Noah and being guarded, but Noah decided to push through the friend-zone and fight for her.
Noah, however, had been fighting a gut feeling the entire time that Abigail may not be his "person."
And so just as Abigail was ready to tell Noah she was certainly "falling in love" with him -- after Noah had already expressed his love days beforehand -- Noah decided to end their relationship and let her down gently.
Abigail admitted that she felt lied to and betrayed, but Noah insisted he had been upfront and honest with her throughout the whole process. Noah said that while Abigail is "perfect in so many ways," he worried that she's not the perfect girl for him.
Abigail and Noah both left the show single, crying and alone, but Bachelor in Paradise provided viewers with an update on the couple at the end of Tuesday night's three-hour season finale.
"Noah and Abigail left Paradise and realized they missed each other," according to an onscreen graphic. "They are hanging out and taking things...SLOWLY."
News of Abigail and Noah's romantic reunion had leaked out prior to the finale.
In an August 13 sponsored Instagram post on Abigail's account, she posted a video of herself in which she was wearing a thick gold link-chain necklace.
A follower of Bachelor fan account @bachelorettewindmill pointed out how Abigail's necklace in that video appeared to be the same one Noah had been constantly wearing while filming Bachelor in Paradise.
Fans therefore questioned if Noah had given Abigail his necklace as a sign of his affection, which would then indicate they had reconciled and gotten back together.
Reality Steve spoiler blogger Steve Carbone reported in late September that Noah and Abigail had been seeing each other post-show, and on October 1, he tweeted a photo showing the pair at a coffee shop in Oklahoma together.
Noah also posted a video on Instagram Stories this past weekend poking fun at recent rumors, seemingly in response to reports Abigail had hooked up with Clare Crawley's now-ex Dale Moss earlier this year.
A woman could be heard laughing, and so Noah's followers assumed that person was Abigail and she apparently finds the Dale rumors funny.