Re: Games are supposed to be relaxing?
The anonymity of playing a game online against strangers often brings out the inner asshole in people, which is why most of the time I just mute people whenever I can, if it's possible. That alone takes away half the frustration for me.
I've got a decent collection of games, but I'm pretty bad at sticking with one game for long periods of time. I get bored pretty quickly, so rather than carrying on playing, I just switch to another game. Variety of different types of games keeps me sticking at it and keeps my gaming fresh. MW3 is probably the only game on Xbox I play at least a couple of times a week, even though it's become pretty stale for me. The rest I alternate between.
Try playing some more with friends too. When I find MW3 or whatever game a bit boring, or frustrating, playing with a friend or a few friends makes it that much better for me. Usually because even though we're often on the same team, I want to be the best, so it adds a bit of fun competitiveness in.