How can you tell if your girlfriend is cheating on ...

If you are not a jealous or suspicious person by nature and you are having suspicions, you may be correct.  We all have what we call intuition and usually your gut feeling is right.  The only time it is not is when you are letting past experiences influence your thinking (such as being cheated on before).  Keep in mind that there are many levels of cheating with the first usually being an emotional affair, so if you are correct in your feelings, you may be able to catch it before it turns physical. 

There are a couple of clues you can look for that I have found to be good in determining whether something is going on.

Has she withdrawn?  Basically has her attitude changed to where she doesn't care about things you used to do together or calling you and checking in, if she used to do so. 

Has she all of a sudden changed her appearance, either dressing up, changing her makeup or clothing choices, exercising or losing weight.

Does she hide her cell phone/email/etc from you or keep her phone close to her at all times?

 Does she seem to make excuses for going to the store or running other errands (if so she may be using these to see him or to call him)?

There's not a guaranteed way to "know" if your girlfriend is cheating, but I'd like to know what has changed that makes you suspicious? How are things different?

Are the two of you still close, in general? How much time do you spend together? How many interests do you share? Do you have mutual friends, as well as separate ones? 

Rather than accusing her of anything, have you considered trying to rekindle the flame between the two of you? Don't try to smother her, but be extra-attentive. Try to recreate the best part of your relationship, as you remember it, for both of you. It shouldn't be a chore, as I would expect that both of you would enjoy being together that way.

Do remember that emotional intimacy leads to physical intimacy. If you haven't been spending quality time together, really interacting rather than just being in the same place at the same time, I'd be surprised if your sex life hasn't suffered as a result.

If you feel a need to push for an answer, I'd suggest trying to set up a session with a therapist, and speaking with her about your concerns with the therapist as a facilitator. This is a really sticky topic, and a good therapist could help both of you avoid saying things you would regret for a long, long time.

Good luck!

If your girlfriend was cheating, believe me, you would know, when you have been with someone for so long, things change, maybe its you, try and spice things up, have some fun and if things dont feel happier, then its time to worry. Dont be so negative 

My friend is a real womanizer and he has no problem with women who use him to cheat on their boyfriend ( he won't do married woman though ! )any way he has five rules to know if a woman his cheating on some guy .

1- She's no longer as needy as she use to be.

2- She no longer gets angry at you.

3- She's being secretive about her whereabouts

4- She places the focus on your  part of the relationship.

5- She showers you with love though sex ain't getting better.

Listen, I know it is really bothering you to question if your loved one is being unfaithful.  I have been cheated on by the same guy over 20 times. I am no longer with him thank God!  The subtle hits he gave me were- Blamed you for cheating, over protective(more than normal).  Not calling for a long period of time or disapering and can not be contacted.  Doesn't cll you back when she says she promises she will (and for no reason doesnt call back) Super lame excuses. 

  But the three that told all was when they

#1 studering when you are asking them about this situation.

#2 Can't look you in the eye or constatly looking away or down.

#3 Repeats the question you just asked or answering a question with a question.

   Yet sometimes a person may be going through masive changes or grieving for something or someone.

If you know they are going through a hard time, try not to jump to conclustions.  Use what you know about the person to help you decside, follow your heart and ask your self...Is it worth it?

okay i think i have your answer. me and my boyfriend just broke up after 2 years and he thought i was cheating on him, guess what it was true, the way he found out was going threw my texts on my cell and other people. Does your girlfriend turn off her phone when you come over? or get changed really quick before she sees you? if she does id say yes she is cheating b/c shes hiden somthing on her phone and doesnt want you to see what she was wearin earlier with some one eles b/c she prob. looks sluty. She may seem like she loves you. DONT GET ME WRONG she prob does but she prob has someone eles on her mind to. okay well just no this if i am right im really sorry but then shes not worth all your love. i dont no the girl but i seems to me like you can do better anyways. youll be okay - from- a X cheater

It's hard to say 100% how to tell.But first sign is your "6th sense" that usually tells U that something is wrong....Other signs can be that she has "secret"phone calls that she hides from u...etc...The best thing is talk to straight to her even though that can be not sufficient cause she would probably lie anyway even it's true....I wish u good luck but as I already mentioned "the 6th sense" works..It worked for me and then I found bunch of evidence of my ex cheating on me...That's why he 's ex now....

Body-language is a good indicater of how someone is feeling. be open and ask your girlfriend questions about where your relationship with her is heading. You can tell if she is lying by rubbing her nose when she mentions certain topics?  For example, you can ask her questions like "so what did you did you do last night?" If she is lying about what she did, she would be rubbing her nose.  No doubt you can tell if she is angry about your questioning if her arms are crossed. Well anyhow, those are my two-cents.