I think this is the issue:
you guys seem to come at it from the point of "I am the better man and if I carry on being like that she will not cheat" with her ex fuck buddy.

Whereas, I come at it from the point of view that it makes me unhappy knowing that one of her friends used to be with her intimately - maybe you heard/know a few of the scenarios, sex stuff they did, or something.

I just think changing my standards might make me happier but am not sure how to get past some of them.
Anyway, that about covers it...as you say...going round in circles.
Thanks

People cheat on each other for all kinds of reasons...you can't nessarily control all of them all the time...what you can control is yourself. And not being controlling, insecure, jealous, intrusive, obsessive, suffocating, needy, paranoid, judgemental etc within a relationship dynamic will go some way towards making any relationship more healthy and therefore reducing the potiential reasons someone might have to want to stray or walk away...

Not sure if you read the 2nd part of my post...cheating is not the issue.
It's the fact that seeing someone who she was with in the past, is annoying / leaves a feeling of resent as you know what they have done together.

You'd only know because you asked. You can't control anyone's past including your own. Look at it this way how is your hypothetical next girlfriend supposed to win...if she's a good honest girl and says...

'You make me so happy and I love you so much that's why I want to tell you so it's not an issue down the line....but my dad used to touch me, when I was 18 my first proper boyfriend made a porno with me then put it on the net after we broke up, I got spit roasted by a couple of scouse lads in Malaga one summer but I was drunk and it was a mistake, oh and I used to suck off my married geography teacher...just thought you should know.'

...you will freak out.

Which means if she actually LIKES you, she's gonna HAVE to LIE to you. And if you have her lying to you off the bat what's the reason not to keep doing so?

And also while we are on the subject what about rape/abuse? Some girls won't have always had much of a choice in terms what sexual experience they've been exposed to at what point in their development? Are you telling me you'd be judgemental of that too? I've lost count of the amount of girls Ive know that have been victims of some kind of abuse/harassment of some kind or other. Often they were prematurely sexualised as a result. and subsequent sexual experience was motivated by a desire to take back control of their sexuality/sexual identity. So where do you draw the line? A cool hot girl that once sucked off three blokes in the year above at the same time behind a bike shed for half a splif when she was a fucked up frumpy 14 years old... was she being 'a slut' or was she being exploited? If you get on with her like a house on fire and love her to bits and the sex is good TODAY...it shouldn't really matter either way right?

Whilst your point is true that by not being those qualities will make the relationship more healthy (and reduce potential reasons someone might cheat),

I think MOST people will at some point feel SOME slight jealousy, paranoia or insecurity and this can sometimes lead to obsessive, needy, intrusive, obsessive or suffocating behaviors.

You have to try to spot when you are being like this, and STOP IT. Go tell a fucking shrink if you have to but don't portray it all onto your girl!