I need help what should i do? i have a dog a pit very very friendley?

all she wants to do is lick people and be peted. me and my boyfriend have her roxy which is 6 months and a cat but when they are together they run and play but my bf is afraid that the dog is going to bit and really hurt the cat. so he never lets the dog inside the house always just sitting on the back porch. i dont think its fair to roxy its mean ?