Is Sex an Expression of Love?

I think there's a time when sex can be an expession of love, but not always. Sometimes because the person feels accepted when having sex, recognizing that someone is actually attracted to them, it lessens their sense of rejection and low self-worth, so they feel loved. I think this usually happens when the other person actually loves them. They can sense it. But I think that most of the time, sex is not an expression of love, but only of sexual desire.