How would you go about doing this?

You should tell her that you feel very very insecure right now and a little sad. Then ask her how she feels about you, and tell her that the thought has crossed your mind that she might be interested in someone else. Tell her that this thought makes you very sad, but that you care so much for her that if there's someone else, you would rather let her go than make her unhappy. Prepare yourself, in case you're right about your suspicions, and be prepared to smile and put it behind you if she says there is no one else.

I would just sit her down and tell her I needed to talk. "sorry I'm being a little insecure here" or some kind of introduction like that, but just ask her if she loves you and if you are the only one she truly desires in her life right now, she'll get the idea. If she starts to get upset by the implications that you've been a bit paranoid about cheating just make sure to let her know you have no intention of hurting her feelings and you "Trust" her, you've just been a bit worried about her recently. GOOD luck! :)

It depends do you THINK she is cheating or KNOW that she is cheating. As a female, I would be hurt if my bf accused me of cheating. A relationship has to be built on trust, and at times it can be difficult to trust another individual. I would hold off on questioning if you are not sure, and just monitor her behavior for a while.

You just have to trust that she isn't cheating. Until you have physical evidence, then you're better off not talking to her about it. Chances are, she'll get pissed and leave you.

I am a girl, and if i was a guy maybe spy on her first. Then when you are sure that she might be cheating catch her when she is with another guy and then break up.

Allow her the upper hand by offering her assurances of your own insecurities first and foremost before you inquire. That way, her response will be more controlled (if she's intelligent and mature). Guilty people usually respond with anger anyway.

Keep dropping on her unexpectedly specially at the times when you suspect she's cheating,asking won't do you good you need to know for yourself.

Say " I know..." and allow the silence to reveal her innocence or guilt. If she plays dumb and says "You know what?", just keep looking at her like you're hurt and repeat " I know..." Eventually, if she is cheating, she'll break down and admit it. If not, you can just pretend you were playing and laugh.

You need to ask, "Would you ever cheat on me?" That answers your quesiton. Observe her reaction, that will surely answer the question. Easily, slowly, take your time, maybe time can reaveal your answer instead of confrontation.

Make sure your facts are right...being accused of cheating is the worst ..