The model called off her engagement to Hefner in June just days before they were scheduled to tie the knot at the Playboy Mansion.
Speaking on The View, Harris said: "We're friends. I've been there a few times since [the split]. It's just so hard going through a break-up publicly..."
The model went on to say that it has been "hard" seeing Hefner moving on with other women, saying: "It's a break-up, it's hard on both of us - break-ups are hard. It's hard seeing Hef and it's hard seeing new people where I was."
Harris, who dated Hefner for two years before they became engaged, added that she is currently single but is "open" to the prospect of dating again.
The 25-year-old also addressed her recent Playboy magazine cover, which was shot before the engagement was called off and features an image of herself alongside the text 'Mrs Crystal Hefner'.
Hefner later referenced the break-up on the cover of the already-printed July issue by adding a red sticker saying 'runaway bride in this issue'.
"That's just his humour," said Harris. "It's fine with the sticker too. I shot it in January. I'm still proud of it."
Lifetime recently aired a one-hour special called Hef's Runaway Bride, which detailed the failed marriage. The special had originally been intended to showcase the wedding build-up and actual vows.
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Watch more of Crystal Harris talking about Hugh Hefner on The View below (US only):