Is "no going out alone with friends of the opposite sex" a reasonable preference within a relationship?

I always see that when someone asks for this kind of thing, they are accused of being controlling, but as I understand it, you’re only being controlling if the other person disagrees and you still try to force them to do something they don’t want to do, or if you know they’re only doing it reluctantly. But is what you are asking inherently bad in this case?

Just to clarify, I’m single, and I’m asking this with future relationships in mind. I’m asking because in uni, I liked a girl who flirted with me, but when I saw that she had too many male friends (and when I say too many, I mean really too many) and was very close with them, I thought it was best to forget about her. Seeing how close she was with her friends, it didn’t seem fair to me to enter into a relationship with her and then ask her to stop being so close with them. It would be like getting into a relationship with a model and asking her to change her profession, and I might end up looking controlling. Although I thought that if I could find a girl who thinks the same way I do about this, it wouldn’t be controlling to have this preference. I don’t know what you all think about that.

Honestly, no matter how much I trust my partner, I just don’t like the idea of her going out alone with friends of the opposite sex. I don’t have a problem with her keeping those friendships, but I think I’m one of those people who believes that when you’re in a relationship, you shouldn’t behave exactly the same way with friends of the opposite sex as you did when you were single (which might include going out alone with them). Some people don’t think that way, and that’s fine, but do you see any problem with me having this preference? And if the answer is no, how should I approach this in the future when I meet a girl? I don’t just want to say "If you want to be my gf, you can't go out alone with your male friends."