Re: is he bored? a guys perspective would be great
Very common thing for a couple that's been having regular sex for a while. Same principal as the new wearing off of a new car.
Gosh, I don't know, maybe try abstaining for a while longer. Let your urges build and get intense before each encounter. I always hated what I call a weak orgasm, that is the feeling of satisfying the tiniest sexual twinge, like on and off in five minutes as you said. Most couples get in ruts at times. Good foreplay is a must for good sex too..
Talk it over. Sex surely doesn't need to get boring. Bad thing is sometimes it does.
Best of luck!