Why is it natural for women to be sensual with other women?

I'm not sure what it is, but I really don't mind making out or being sensual with another woman. I consider my ual orientation to be straight. I'm very much attracted to men and only date men, and eventually would like to get married to a man, but it feels so nice and lovely to be sensual and ual with another woman. For example, one time my best friend got her heart broken by one of her boy friends. She came over and I comforted her. We held each other in our arms and we ended up kissing and making out, and made her orgasim multiple times (I know where the right spots are, hehe). And she is even a straight girl as well. It just seems so natural for us women to be sensual with each other, though I'm not sure why. Can someone explain this to me?