Viewers of the Essex reality show saw cast member Lauren Pope confronting Mario about still speaking with an ex during last night's episode.
Mario admitted he'd spent a day with the unnamed women but that he wasn't dating her or getting back together with her.
However, after the show, the Italian tailor posted a cryptic tweet hinting there were unresolved feelings between himself and the mystery ex.
"Yes… I was talking to my ex," he tweeted. "Can't help what the heart wants."
Mario's most famous ex, of course, is his former TOWIE co-star Lucy Mecklenburgh, who is currently celebrating a friend's hen do in Vegas.
Could it be Lucy? We're not sure… in a recent episode of TOWIE Mario did admit to his mum that he'd been back in contact with Lucy, but confessed himself it wasn't a great situation as he always ended up hurt.
His mum also advised him to cut ties with Lucy.
Maybe it's Pascal Craymer? Mario dated the model last year before they called it quits before Christmas. She hasn't said anything on Twitter about the episode. Or is it the 'third' woman Lauren Pope mentioned last night?
As well as accusing Mario of still chatting with his ex, she said she'd heard rumours he'd been dating another woman for around six weeks and they were even calling themselves boyfriend and girlfriend, although Mario denied this.
Whoever it is, we're imagining we'll hear more about her during Wednesday night's series finale - and we wonder how Chloe Sims feels about it all?
Viewers were surprised to learn recently that Mario and Chloe had been dating in secret for a month, meeting up in London so that nobody found out. They called time on their romance in the last episode, however, as Mario was scared he'd lose Chloe and her brother Charlie Sims as friends if he and Chloe ever broke up.
Chloe admitted that she did have feelings for Mario but she was hoping they'd fade soon.
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