Having sex with someone you lust after is a self satisfying experience. It fulfills a necessity, it can be intense and it can be very relaxing after climax. If it’s doing with someone you like it can be like having your favorite food, a treat.
So when you have sex with her, it is in a way that is more encompassing, deeper in the care with which you touch her body, how you kiss her, how you mind every aspect of the whole thing so that she is comfortable through it all. You are more careful with her.
Looking into her eyes as you penetrate her, it becomes more than just sex. It just does.
Sure it can get very passionate between you two but, it’s just better.