Yeah gets pretty busy during june, july, August because that's winter in Australia and popular with Aussies escaping the cold.

Id never stay in Kuta to busy at anytime, staying down in Legian area is not as busy and better beach breaks or check out seminyak if your girl is into more upper-class, hotels/shops/restaurants.

Dont know what kind of budget your looking at but check out puri raja hotel in legian, http://www.puriraja.com/ its mid budget right on beach in a good area, many other lower budget options in that area if you dont want to be beach front.