Okay, first let's clarify this,

THIS IS NOT RAPE!

Now that we have that covered, let me explain ^^
So, this is obviously Rampage Sonic and Amy, hence the red feline eyes. (If you have no clue what a Rampage is you might want to check this [link])

In a relationship between two Rampages, the female is the dominant one. She's the one that usually forces things, like this, upon the male. The only time when she has no control is when it's time to mate. That's the males job to make a move towards the female.

And don't worry, she's not hurting him
Rampage Sonic's just surprised, that's all ^^