Christian and Cleo had a fairly small amount of screentime on Season 6, Episode 15 of 90 Day Fiance: Before The 90 Days.
They grabbed breakfast and talked about Christian’s upcoming return to the US.
Well, he talked. She worried.
Having seen Christian chat up women in bars and invite a stranger to dinner, Cleo worried how much of that he’ll be doing when she’s an ocean away.
Christian and Cleo

Thus far, Christian hasn’t had a traditional “English breakfast.” That is for the best. If someone handed me a plate that had beans, sliced tomatoes, and mushrooms on it, I would take it as a death threat. Anyway, they opt for something sweet, and get some artisanal doughnuts. But with Christian’s imminent departure for the US, some of the red flags from their relationship are weighing heavily on Cleo.
Will Christian remain committed?

Speaking too quickly because she’s feeling anxious (most of us have been there), she admits that she feels nervous. The idea of Christian approaching women in bars — as he’s done during this trip — is unsettling. Especially since he won’t be coming back to Cleo at the end of the night when he’s back home.
Christian doesn’t like that

He doesn’t believe that he’s done anything wrong. Or even that the way that he approaches single women in bars would make them feel like he’s hitting on them. And Christian also doesn’t want to feel boxed in. Interestingly, a few viewers have commented that they don’t think that Christian’s “social butterfly” tendencies have been out of line. This could be a compatibility issue. Anyway, Christian does affirm that he’s with Cleo and not looking to date anyone else. (Just invite them to dinner, if Thanksgiving was any indication)
This is a lot

Cleo begins to cry. She’s obviously going to miss him, and this is an emotionally heavy conversation. Christian reassures her, wiping away her tears. “When I’m with you, I’m with you,” he says. And he reminds her that he could just stay single if he wanted to pick up random women. Cleo worries about bringing this up; she doesn’t want to change him, but his behavior really worries her sometimes.