Found out that partner had been messaging a woman he's met through work a lot (by met I mean messaging & calls, it doesn't seem.like they've met in person).
There's lots of mundane, even day stuff in the texting, alongside flirtation, but in the last couple of days it became increasingly sexual.
He asked whether she'd ever had a threesome (in the context of her saying she'd worked in a certain environment with lots of good looking young women when she was a lot younger), she said no, but he escalated that to talking about a threesome involving me, then sent her a pic of me. He'd told her i was gorgeous, and she said that wasn't really high praise given he says she's gorgeous etc. and she's not. He sent the pic and said "see, do you trust my judgement to call a woman pretty" etc.
She asked him what my opinion of a threesome was, and he answered "haven't got that far yet".
We're together nearly 20 years, 2 kids.