Signs your boyfriend is talking to someone else.

If you ever caught your boyfriend cheating or talking to someone else because at the moment I’ve caught my boyfriend going on girls instagrams and liking the pictures and following random girls and whenever I come in the room he has his phone so close to his face and he turns slightly away from me so I can’t see what his looking at and I’ve asked what his looking it and he just says ‘nothing’ I’ve asked him before if his been talking to someone else and all that and I just get ‘of course not’ and it’s stressing me out not knowing.