you can tell be spying on them!
First off take the time to think about who you are, and that you aren't overly jealous and second-guessing scenerios re your boyfriend and other girls. If you feel you have good cause to doubt where he is and with whom, then communicate this to him! Of course there is no doubt between us that he will deny every single bit of it if he is guilty, but look in his eyes (the windows of our souls) and if he isn't looking you in the eye, or his body language (shaking, red in the face, shifting from one foot to the other or turning his back on you) then he's lying! Tell him if you ever catch him cheating (and you will) that's the end of your relationship. Tell him the ball is in his court and you'll be watching! Remember, now you have put the seed of doubt in his mind and he won't be so sure of himself if he is cheating.
If you really think he is, the other poster said it .... "spy on him!"
Good luck Marcy
I am a boy, so you should just ask him or spy on him Telling if someones cheated on you is simple. The next time you think he's out with the girl, just send him a text that says "I know," nothing else. Then don't reply to his texts for a few hours and eventually he will tell you, and if not then he's probably not cheating and just say you accidently text him, you meant to send it to a friend then your phone died. That is, if you feel justified in lying to him.
If he starts hanging around other girls more than you, then he is definitely cheating on you. If you and him are not as close as you should be, and starts looking at another woman and starts being near her a lot, then definitely yes.
If he hugs or kisses you every time he comes home that means he is cheating on you
if he makes you happy in any way he is cheating on you.
BREAKK UP WITH HIM NOW !!!
Ask him :/
You tell the truth and accept the consequences.
In most cases if a boyfriend was not cheating and was accused by his girlfriend then he would be angry and since your boyfriend is silent there is a high possibility he is cheating and cannot own up to it.
Tell him the truth, say you like girls.
No. Blackmail would be if you went to the boyfriend and threatened to tell on him unless he paid you something.
You should tell your friend that he is cheating its best that she knows.
Ask them!!! And if you are wondering they probably are.
Well he might make excuses to not hang out with you..
He's either cheating or watching strippers
You can just tell her if you don't want her to be anymore.
Lie and tell him you cheated on him... he'll tell you just to get even with you.
Just tell him everything.. and hopefully he will understand and appreciate that you told him.