This poem is all about sex. But wait, you say! There are no people in this poem! How could it possibly be all about sex? Well, let's just put it this way – if we could actually turn the flower into a woman and that bumblebee into a man, we'd be looking at some pretty intense material.
Not to put too fine a point on it, but we're going to go ahead and say that "he's in there as she sways. He utters thin / Sizzling bleats of difficult enjoyment" (8-9) is about as risqué as you can get without actually naming the deed. There's also a lot of undressing – "she'll throw off her skirts" (16) and "that stripped, athletic leg" (25). The flower is a sexual being here, no doubt. So grab something to fan yourself off with as you read this poem – it may not literally be about "when a man and a woman love each other very much," but metaphorically, it's all there. Phew! We're blushing now.