It's been three months and you're obviously not taking this relationship seriously, so why should she?
You two were so young and carefree a few weeks ago, but it quickly became apparent that you weren't willing to put in the effort to beef up your gaming reputation. To be fair, she did chide you for your small collection of achievements, but that was just teasing, right? Guess not.
Turns out that dude Mark she's been texting with has been sending pics of his gamerscore, and like, wow; there's no way you could compete with something that size. Talk about emasculating. At this point it's too late to win her back but you might as well buy some new games and try to get serious about your achievements moving forward. Or maybe you'll get lucky and find a woman who doesn't need something big.
Good luck, chump.