All you gotta tell her that you dick is very sore, raw, and red from fucking too much. Give it a few day break. Girls get the same way, and I'm surprised she's not the one complaining about being sore.

And it also helps if you use lube, especially when you're having a lot of sex. Girls will eventually stop getting wet during sex, esp. if it's for a long time. So that in turn causes friction, which makes guys and girls raw/sore in the end. Just use lots of lube when you feel her drying up. That will help a lot.

But if you can stop the soreness from sex, then hell no it's not bad to have sex 3-4 times a day. No harm in it at all.