if he's trying to blame you, he's a creep
Anything can happen in sex.. At times either of will miss the sync and left out.. Nothing serious to think too much on that.. Just laugh it out.. And make things easy and move on for the next time...
Could be any number of things, distraction, the woman laying there like a dead fish, too much ****, etc.
Not necessarily. Maintain an erection is a fairly complicated physiological process. Things unrelated to his attraction to the woman can cause problems.
No, sometimes it means he's stressed
or distracted, maybe only momentarily
could be a medical problem
Could be he's getting tired, or sore... maybe having TOO MUCH sex in a short time span
or yea - possibly also that maybe he's losing interest.