On the subject of lying.
1: When you meet a new girl, you don’t have to tell her at all your starting a relationship with her - you’re not lying because you never told her you was committed to her in the first place.
2: You can be honest with random women you meet - "hey I have a GF, but I really like you and I'd like to get to know you better" - Some women won't go there but you will be surprised how many will - for example there are women who just love to date married men, for example. Personally I’ve had sex with women whilst telling them this in a club - "Hey we have a connection, but I’m not really interested in a relationship right now, but I think me and you can have some fun regardless, what do you think about that?". - Works a charm.
Are you lying to your current GF? Are you married? No?! If you’re not married to the girl, in reality it does not matter if you cheat because you’re not fully committed to her.
And STR8UP is right, women and men see cheating differently - A women could infact like you more, if she found out your a catch, a stud or have options beside her - she will infact try harder to please you.
It could go one of two ways, depending on how much she is into you.
If she is just with you, to fill in a gap - she will probably dump you at the first sign of cheating - but if she is so into you, she sacrifices nights out with mates, cooks for you, buys you shi* and as your picture by the side of her bed or in her purse - There is a very high chance she will try 'harder' to please you if she suspects your looking else where - Don’t be surprised if your girl starts to diet, or buys you things out of the blue, or leaves little tokens around your house, like lady things - A pair of shoes here, some nail varnish - Prop like things she leaves incase the competition comes over and see's the other women’s shi* in your house - She may leave a dress, she will buy a cra* dress, pretend to wear it, when you object she will leave that dress at your house for a 'special occasion', when in reality she is marking her territory.
It’s not that you have cheated that a women gets upset about, its more or less that she could lose you to another women. Where as a man's pride is hurt or damaged a women is thinking more on the lines of - 'whats this other women got, she better not take him off me' - In essence they are more concerned with the other women, then they are about you. The manipulated Man talks about this in detail.
I've also seen this first hand.
Also the hardest thing about seeing different women is remembering what you did with said women.
For example a good few times, I lost a few plates by talking about things we did in the past, but in was actually talking about things I’d done with another girl - Funny afterwards, but not great when your plate does not return your calls, because you've just been describing how you fuc*ed her in the garden, when infact it was the other girl, you'd been throwing around the bushes.
Also women want to be exclusive - I know of none that would have been happy knowing I was fuc*ing other women - Even if they suspected, it's best to keep it that way - don't make it known, don't advertise it and do not brag about it - Keep it secret, if she suspects but cannot find out because your smooth, all the better, she will try harder to 'get you', but if you rub her face in it, she will be out the door and probably be very upset, depending on how she is into you.
Be careful of her friends too - She will make you meet her friends - Part of this reason is because if you’re out on a night out and you do something, there is always a chance one of her friends could be around to see you. So limit your interactions with her friends if they are local, you don’t want to be bumping into them on a night out, or at least find out the places they go to and avoid those places -
I picked up a girl, whilst seeing another girl a few months back - it turned out the girl I was seeing was out with her mates and they were in the next bar from us - 1 minute away - we left the current bar and 2 minutes later she walked into the bar. That was a lucky escape, what can I say I must lead a charmed life.
If your girl suspects and she says "have you cheated on me". What you don't do is chump out and get defensive, instead you say this "Yeh I had a couple of blonde Swedish girls around the other night, I'm thinking about asking you to join us" - give her a big smile.