To me sex is something to look forward to with a spouse. It is not something to be done lightly because you are lonely, or want some fun. It should be done in a marriage between two people, knowing that you are honouring God and your partner by waiting. Sex is like glue it melds two lives together like contact cement or the glue for those plastic model kits. When you build them you don't just start slapping glue on things then see how they fit. You test the connection so you know how or if they fit long before you put glue on the parts. If you don't you can get the parts seperated but it is difficult and bound to leave parts of each part on the other.
That is why relationships based on sex are so painful. Sex glues two people together and then when they are ripped apart it leaves bits and pieces still stuck to one another.