How does one know?

I've been talking to a friend. Now I know some of you are reading this and thinking "Yeah, right, talking to a friend. This is actually just all about Ann but she's doesn't want you to know." Trust me, this is a friend's situation. Trust me.

Anyhoo (to quote Stephen Fry of all people). My friend has a problem that involves her husband. A married woman is flirting like a good 'un with her other half.

He receives calls and text messages at all hours. When he is sitting next to this 'other' woman (in an entirely legitimate context) she leans across him and brushes against him and whispers in his shell-like. OK I made the shell-like bit up but actually it wouldn't surprise me.

He tells his wife he's not at all interested and, frankly, I believe this. But how does one know?

I'm sure he'll be flattered. I'm pretty sure he's not been tempted to do anything other than be on the receiving end of some attention. But, and it's an important but, he's done nothing to fend off this attention. It would be awkward to close things down but not impossible. I think it's possible to demonstrate, with just body language, that flirting is unwanted.

How can my friend know that nothing more significant has happened and how can she allay her fears?

Oh, and if any of you are thinking I'm the other woman - forget it. What were you thinking? Honestly!!!