The purpose of sex...
At first, it was purely because I needed to have sex, because I'm a man and I have needs. I need a woman to satisfy my needs. When I'm having sex with a girl that I'm not romantically involved with, there's no passion or intimacy there, and the only purpose of sex is to satisfy my physical needs.
It's completely different when it comes to the girl that I love. The reason I had sex with her was because she was completely irresistible, I loved her deeply, I felt that sex brought us much closer together. It was an amazing experience making love to her, I remember every moment of every time. Sex never felt the same with other women, no other girl is as good as her. The reason I had sex with the girl that I love was to satisfy her needs and to make her mine. Sex brought us closer, it was a very important part of our relationship and I'm glad we were able to share that. It goes beyond satisfying my physical needs, I'm in love with her so she's more than just a female body, much more than that. It's very hard to explain or to put into words. Also, I had to make sure that she doesn't get it from anyone else, as my woman it's my duty to make love to her to make her feel how much I love her.
Sex is completely different when you have it with a girl that you love, compared to having it with a random woman. Completely different.