My daughter has a group of friends that she socialises with and a couple of the mums show up in Facebook photos on their occasional nights out. Although I have no interest in those types of night out, I was curious about how these mums always seemed to be there, so I asked last week. 'Oh, I know' said my daughter. 'It's becoming embarrassing - J and D (their daughters) don't want to offend them, but they need a break. They keep assuming they should join in every time. If it was you, I'd just tell you straight!' She would, too 
My daughter then went on to say she appreciates I need my own friends, so won't barge in on us (has joined us for coffee once) and she values being able to choose whether she can spend time with me, with children or not, as you won't always be a free agent, mum, and I'll be spending a lot of time with you out of duty!' Cheeky madam! My other daughter would tell white lies rather than be brutally honest and cause offence. I'm sure there's a middle ground somewhere.
Don't fume, Katy - I'm sure she loves you and doesn't mean to hurt, but maybe you could tell her gently that you want her to feel able to be honest with you? 