My answer:
A cloud.
The last time you were hot,
I cooled you down,
And you praised me.
Clouds cool things down.. with rain and such.
But yesterday you said
I looked "big and fat,"
And I was sad.
Clouds can be big and fluffy.. the person in question must have taken notice and remarked that the clouds were remarkably big and fat that day?
Yet today I felt better
when you told all your friends
that I looked like an angel.
Angel, heavens, clouds. Probably a cloud formation that reminded the person in question of an angel.
When we touch,
I admit I feel like
I'm just annoying you.
Fog is annoying.. reduced visibility and such.
Is out-of-sight really
out-of-mind with you? Or do
you miss me when I'm gone?
Sometimes there are no clouds in the sky, and usually people are pretty happy about that.