Don’t lie, tell us. I would much rather know that I’m not doing something in a manner that’s pleasing her, and be told what I can do to please her…. than to have her lie and find out at some point down the road she’s been lying (which would probably be immensely painful).
When it comes down to it I’m almost always out to ensure that my partner has just as good a time as I am. And if she’s not pleasing me I would tell her how to do so, so why not have her do the same so we can both enjoy it?