The source noted Ashley "cried of course" when Jared asked for her hand in marriage and she is "just so happy."
"She really is excited to be engaged but is more excited that she's found her person. Jared feels the same!" the insider said.
The source revealed Jared proposed with a ring designed by Neil Lane, the jeweler behind all recent Bachelor franchise engagements, and Ashley called her family and friends to share the big news right away.
"[Ashley and Jared] already know they're meant to be," the insider continued. "Jared [is] the sweetest and the greatest. He's really her counterpart. They're like their own little rom-com!"
The couple has come full circle since meeting in Mexico on the set of Bachelor in Paradise 2 in Summer 2015.
Although Ashley and Jared went out on a couple of dates and exchanged a few kisses over the last several years, Jared kept Ashley in the friend zone until they officially began dating in March 2018.
The couple -- who also both appeared on Bachelor in Paradise 3 in 2016 -- confirmed their romantic relationship during the May 22 episode of the YouTube series Ashley hosts, The Story of Us.
The insider told E! News that Ashley and Jared are "so happy" even though things have moved quickly in recent weeks and they are just "perfect for each other."
Since the couple only went public with their romance last month, the insider admitted "it seems quick," but they have "been best friends for so long."
"It's actually perfect because they got to be real friends and really know each other over the past few years... He has been her best guy friend for so long he's part of her family already," the source explained.
Prior to dating each other, Ashley was involved in a relationship with her The Bachelor Winter Games co-star Kevin Wendt. As for Jared, he never entered a serious relationship except for trying to make things work in the real world with Caila Quinn after Bachelor in Paradise 3.