Love is the way you express your soul. It is the way that you feel when there is something you care about and are willing to go above and beyond to do something special to show that you value that over anything else in your life at that time. The real part of me wants to agree with Vod, but I feel if I belittle love that much, I will not ever find it.
Like you sad: Love is the way you express your soul.
There are people who actually never feel this experience. They are in the relationship with their partner, they hanging out, going on parties, traveling, having a sex but when you ask them: Do you love him or do you feel happy with her, the answer is... I don't know.
The sex is something that you should first experience with your soul. If you can feel that you can make love with the person on that level, then be sure that you are with the right person. If he/she is not able to feel the way how you express your soul, then it's better to leave.