I tell my husband that I need to go upstairs to do something, and then I sit in my daughter's room in her rocking chair petting my cat. It's very calming and he hasn't caught on yet that I really don't need to do anything up there!
I think an ever safe option is to say " I need to go pick up something from the pharmacy....woman things..." no guy will touch that one, then go to CVS or wherever, get a chick magazine, a soda, and sit in your car and enjoy 30 min or so!!! Hey, no lie was told!
I like to have my private time in the bathroom but now I can't even do that because she just learned how to open doors. We have a lock but it is hard to work.