Some thoughts about my girlfriend's sexual past

[DeistPaladin]

And don't put words in my mouth. If a girl came on here and was pissed because her boyfriend of 3 years had a bunch of partners before her, I'd tell her to get the fuck over herself.

And I think that last point speaks to another reason why he's being called out. There could well be a double standard at work here. I'm not saying I've done everything on the list offered in the OP but I check off quite a few of the boxes. I'd have been devastated if my now wife had broken it off with me just because I had a life before her. If our gender roles had been reversed, would I have been in greater danger of being dumped?

Now that I reflect on it, and I'm just musing as I type, there was one previous girlfriend that expressed some concern over my past but it was nothing that couldn't be overcome with some reassurance. And no, we didn't end up breaking up over that but another issue. Women worry about issues of fidelity too, so some "concern" is understandable either way. 

Maybe if you (I'm speaking to the OP here) just talked as honestly about what to expect from each other going forward. If you need a committed, monogamous partner, just say so. 

Our society also has a double-standard applied to men as well. While women are subjected to "slut shaming", men are made to feel like their garbage if they're not sexually active or if they don't have an impressive sexual resume. If she's had a history that makes you (the OP) feel envious, it might help to be consciously aware that this is a problem of irrational insecurity for you to work on. Being honest with yourself and her might help you through this.