The basic problem is that male/female sexual market value is extremely lopsided.
Your girlfriend breaks up with you she can have another guy within a week or even that day, even if not a bf definitely she can grab a hot guy from a bar for sex. Truth is most girls have more than one guy lined up to take your place that she calls friends. Of course she will get upset if you suggest they want to get into her pants. It's bullshit, women don't let go of one vine until they have another prepared. Often your girl wants to break up with you for six months or a year but she won't pull the rip cord until she has someone appropriate lined up. Usually, this is the case.
That is why most men get blindsided, they think things are going great when the woman has not been satisfied for a long time. The most common reason for boredom is guys when they get into relationships cut off their friends and throw away their black books and start
hanging out with her friends. This isolates the man and sets him up for failure as the woman sees he has no life or options other than her. When the breakup happens the guy is often completely isolated and falls into a depression.
Now you on the other hand, if she breaks up with you it could be six long months of masturbation before you can replace what you had, maybe longer if you go into an emotional tailspin. What this means is she has all the power in the relationship.
But if you are a player and you keep 5 fuckbuddies she has no power to tell you shit. One of the girls on your list has a headache, you call the next number and she'll have to catch up with you later. The key is you don't tell any of these girls about each other and don't make any verbal commitment but don't tell her you fuck other girls. Let her wonder. That way when you blow her off after a fight she will wonder how you are so cool about it. Maybe she will see you out with that other girl and then she'll really go nuts. Tell her she's just a friend but she will read the other girl's body language believe me.
Let her see you with these other girls but don't introduce any of them as girlfriend, say they are just friends and stop being so jealous. YOu can invite these girls to the same coffee date and they will not figure it out.
All they know is they have competition. I used to do this all the time, I would invite an ex girlfriend who I was still fucking to meet a new girlfriend for coffee. You could see their hamsters going into overdrive and it made things smooth sailing with the new girl because she knew she better reel me in quick. Later I told her we used to fuck a lot but we were just friends now, if she would complain I would get indignant about it and say "am I not allowed to have friends Hitler?". My girlfriend hated it but it kept her on her toes because she knew if she doesn't put out the other girl might get her old place back.
There is nothing to worry about because there is a wall of jealousy that makes collaboration with the enemy unlikely. She just knows that bitch is sniffing around my man. lol
Of course you can seriously date one of them and have girls on the side and just not give a shit. If caught you'll laugh and chances are she'll stick around anyway when she finds out how valuable you are. She'll fight for you in many cases so don't worry about it.
A woman would rather have half a winner than all of a loser.