"Honestly, if I was a betting man I would say it would happen within the next year, yes," Colton, 27, told ET.
But in the meantime, Colton said he and Cassie are just "trying to live as normal lives as we can" amid all the craziness and media hype that follows starring on The Bachelor or any of its spinoffs.
"We're enjoying it, we're having fun," Colton shared.
"I think, right now, at this point in our relationship, we're enjoying this, trying to be as normal as possible. But you know, we've talked about our engagement and talked about taking the next step in our relationship and [decided] one thing at a time."
Colton appeared completely taken with and astonished by Cassie, a 23-year-old assistant speech pathologist, as she walked the red carpet in a shimmery silver and black gown. He gushed to reporters how beautiful she looked.
If Colton decides to pop the question any time soon, Cassie would most likely accept his diamond engagement ring.
After The Bachelor's Season 23 finale aired March 12 on ABC, Cassie revealed to Kelly Ripa and Ryan Seacrest on Live with Kelly and Ryan what her answer would be if Colton opted to surprise her with a marriage proposal that very day.
"If [Colton] asked for your hand in marriage, what would you say?" Ryan asked Cassie flat out, putting the pressure on.
"If Colton were to ask me... it would be a 'yes.' But no rushing! We're not rushing it though!" Cassie replied.
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Colton announced at the time he had moved from Denver, CO, to Los Angeles, CA, to be closer to Cassie, and then about two weeks later, Cassie revealed she was also moving about 40 miles north from Huntington Beach to an L.A. apartment.
But when Colton spilled his guts to Cassie and professed his love for her before the Fantasy Suite portion of their date in Portugal, Cassie determined she needed to quit the show because she didn't reciprocate such strong feelings yet.
Cassie also felt she wasn't ready to accept a marriage proposal from Colton and wanted him to leave the process with the happy ending he had hoped for.
Colton, however, refused to give up, and after dumping both Tayshia and Hannah G. in Portugal, he begged Cassie to simply give him a chance and date him -- with no expectations of an engagement.
Cassie obliged and then traveled to Spain to meet Colton's family while cameras were still rolling. Once the show ended, Cassie slowly fell in love with Colton in the real world.