KC famously dated co-star Michael Goonan after splitting with Drew Brauer on the show.
Jason and KC were spotted on the Gold Coast together along with fellow MAFS alumni Cameron Dunne and Jessika Power and later seemingly confirmed the relationship on Instagram.
In one photo, Jason is seen with his arms wrapped around KC as he plants a kiss on her head.
He captioned the snap, "You miss [100 per cent] of the shots you don’t take," with KC commenting on the photo with a loved up emoji.
Jason's MAFS co-star Bryce Ruthven also commented on the post, writing: "There's a keeper!"
Another former MAFS groom, James Susler, also commented, "Aww... Love you guys."
One follower wrote, "She is such a sweetheart, you two make a beautiful couple."
Another added, "OMG you guys are so cute together."
KC also shared a number of photos of herself and Jason, captioning a series of photos, "I mean sometimes you just have to let your hair down... Thanks J for a fun weekend."
He responded in the comments: "Anytime xo."
Jason shared a video over the weekend of KC with his nieces, joking: "Well I'm now invisible."
The pair has been leaving flirty comments on each other's Instagram posts for a while now.
Jason's ex-'wife' Alana, confirmed to Yahoo Lifestyle they broke up due to the controversial leaked video of Jason, along with co-stars Georgia Fairweather and Johnny Balbuziente, making fun of bisexual groom Liam Cooper.
"Well, obviously the controversy was something that ended our relationship, so it impacted me in the way that Jason and I are not together anymore," she explained. "We were never able to get past that controversy.
"So, it obviously affected me in a big way and it's unfortunate that had to happen, but I know I tried to get through it as much as I could, but we never made it."
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