If you win, you just beat up a girl.
If you lose, you just got beat up by a girl.
If you tie, you have as much skill as a girl.
That's why you don't spar with girls.
I think you are looking at this from the wrong standpoint in some ways. One of the reasons for sparring is for people to get a feel for how to apply that which they have been learning about and practicing hitting the heavy bag and focus pads with. That does not mean you have to throw things at full power so take some of the power off of your techniques and combinations when fighting those smaller, lighter framed, and weaker than yourself. When you fight those your size or bigger then you can and will need to use more power.
Also even though you might not be throwing things with all your power you can still learn from sparring with her and she when sparring with you. Sparring is just not a situation where you beat the heck out of each other and prove your physical toughness nor does it have to be that every time. If that is the thinking and approach that is largely emphasized though at this gym or school then that says something about the quality of the training you are getting.
There are many technical aspects to fighting and defending yourself and you can always be working on them and understanding them better when sparring with someone of lesser ability. Working on your defensive skills and countering for instance rather than being overly aggressive and just dominating them because of your greater size, weight, and strength for instance is what I am suggesting here.
Stop looking at sparring as a means of hurting and dominating others all the time. Instead start looking at it as a way of learning to apply things more easily and better and developing your knowledge, skill, and ability to do that if you truly want to be a good fighter and good at MMA as far as the stand-up applications go.
So don't go hard. If you can tell that she, physically, won't be able to you going at your normal intensity, dial it back. Work on fancier, more technical aspects of your game. After all, sparring isn't about winning, it's about learning. If I beat up a smaller training partner, all I've really learned is that I can beat up a smaller person, and, well, duh. I didn't need to spar them to know that. So when facing someone you know, or think, you could take, then create your own challenge by working on things you're not good at, limiting the types of attacks you use, letting them attack first so you work on defense, etc.
Now with that said, they may not suck as much as you think. There are women in this world I'd rather not be hit by. You could be paired up with one of them.
Girls can just be strong as men. Ronda Rousey is a great example of a female martial artist in the Octagon. Seven straight victories and still counting. She is also going to be one of the next TUF coaches fro the new season, serving on the men's division.
If you focus entirely on logical calculations and decisions, you won't have enough time to "get hard". However, if your concentration lapses and you start daydreaming, then you'll have an issue.
Just keep everything really slow and low power. Keep asking her if she wants you to step it up. Use communication to get an idea of what's going on. Don't just sit there with your own ideas of what should happen.
I'm a MMA fighter, and a woman. Number one thing don't be friends with that person. You're going to look bad if you loose to a girl. Just imagine she want to kill you...
Don't worry. Once she nails you hard a few times your feeling will change.
Ask them to put you with a boy and explain them why.
I've started taking classes about 2 months ago and they put me with a girl. It felt weird and I couldn't proceed. I know she's there for a reason but ugh, if I go hard I'm going to feel terrible.
I guess if I'm going to learn I have to do but I don't know. I've never hit nor did anything physical with a girl in my life. Any way I can get rid of this uneasy feeling?
