you're right about the nature of difficulty being cause for frustration, i find street fighter 4 frustrating because i can't consistently land 1frame links and the reversal window is too large allowing cheesy shoryuken spam
fallout 1 i dont find too frustrating because you can save midfight, so ever 5 minutes or so i save again just in case a rogue eyeshot knocks me into heaven. it's not a huge deal, but it would be nice if the crits werent so insanely damaging and random in nature, but it never seriously bothered me (i just like playing on easy so i never have to worry about combat in that game since i play more for the dialogue than the pewpew)