How to I get him to be rougher?

Ask him to be. Be dirty. He'll come around.

tell him, if my girlfriend came out with a fantasy like this I'd probably cum in my pants, and then go for a wank to relieve myself

Just tell him before, during or after sex "donkey punch me right now!"

Just let him know. I was that way when I started off. My rough and her rough were two different things. Once I understood that she wasn't as fragile as I was making her out to be, we worked on the roughness. Just work with him. If he is thrusting soft, tell him HARDER! If he is holding on softly, tell him to GRIP IT! Eventually he will get better at it. Also make sure he wants it rough. If he is not all into it but willing to try then compromise and give him a moment of you on top doing a slow and gentle grind while he rest. He'll love it and you'll love it. Also try wrestling with him. I mean really get on him, maybe a hit or two in the side. The mix and mingling of our bodies got me so turned on and I got rough having to pin her down to the floor or bed or wherever we were. =) Finally if all else fails angry sex is always good rough sex. Just a little fight with him and then a good making up job.

First of all you need to sit down and talk to your man. Tell him that the sex is good, but you like it rougher. When you start having sex tell him how you want him to do it. Plus before you have sex play little sex games with him. Get him to spank you and you spank him and try little things to spice it up in the bed room. I had that problem with one of my partners. I told him I liked it rougher and wanted it to be more sexual in the bed. Now he turns me out, so just talk to him, or rent a porno with a lot of rough sex and good positions that you think you would like him to do with you. Eventually he will try to make the sex better. It is worth a try.