It's just that you seem abnormally cheerful for someone who knows he's being, as they say, set up.

Ms. Frost is remarkably cheerful for someone who has spent the past year on the road with no fixed address.

He was being too cheerful for that, which made me wonder if it couldn't have waited a few hours.

They said she must stay cheerful for the child's sake.

Use "cheerful" to describe those who did the most menial chores for you.

And his answers were cheerful for the most part.

Or is he pretending to be cheerful for his companions' sake?

But more recent studies have been less cheerful for advertisers.

Do try to be a little cheerful about it for a change.

I'm going to die, but they do not want me to, and so I try to stay cheerful for them.