Need help

So recently my boyfriend has been acting weird. He’s been more secretive with his phone and some of the stuff he tells me just doesn’t add up. I’ve spoken to him about this but he tells me it’s because he’s going through a rough time and needs privacy. I’m all for understanding but deep down I feel like that isn’t true. I was wondering if anybody would help me by messaging him through Instagram in a flirty way acting as if you were looking to do something with him and tell me what his response is :/