http://www.cnn.com/2015/05/26/living...130pVODtopLInk
This CNN article got me thinking. I would say no it's never okay. I've been in relationships before where my girlfriend would be like "Let me check your phone" and I would tell her no. Not because I have something to hide , but because I value my privacy. In my opinion, just because you are in a relationship does not mean you give up your privacy. Plus you should have trust in one another. Snooping never ends well.