I tend to agree with both tinyrabbit and Hamster.

In regards to he game, I think the boyfriend just didn't even think about it. For some reason, he felt like playing the game on Saturday instead of Sunday... maybe one of his buddies had a conflict. Maybe he wanted to change it up. Maybe he thought that since you hang out every Saturday, skipping one Saturday wouldn't be the end of the world, especially if he planned on seeing you on Sunday. I find that with my husband... Things just don't occur to him the way they occur to me. We're each perceiving the situation differently. And until we talk through the issue, I have no idea what's going on in his head, nor he mine, which can bring about unnecessary fights... So, basically, find out why he moved the game. I'm pretty sure it's not a personal reflection on your relationship. Also, if he again changes the game to suit your regular date night, then I wouldn't be offended. I would let it go. As long as you can communicate about the issue, and both feel heard and understood and content with the result, then don't worry about how you got there.

I do agree that you are probably insecure, and I think improving your self confidence might help. I also think that you are carrying around unnecessary guilt by always apologizing, if not also resentment. You might not be bringing that into the relationship...yet. But if you keep it bottled up inside you and never talk about it, then it's going to explode one day, and there's going to be enough guilt and resentment to go around over and over again.

I can't comment about the ex-girlfriend issue, as my issues with my husband's ex stem from his family and not him... Not to mention they did not have anything even closely resembling a healthy relationship mostly because of her...

In summary... Talk to your boyfriend. Just get everything out in the open.
Good luck