I noticed a while ago that my girlfriend sets her status as "offline" on facebook while she's online, when she asked me if I'm online I said "Yeah I am obviously silly, and you are. We both set it to offline?" and she replied " Oh I did because you tease me all the time that I'm not studying for my exams..and I do but my cellphone shows I'm active"

Now though, after time we haven't discussed she did it on instagram too with the new version.

Could she be trying to hide her status to make me think she's offline while she does shit behind my back?