Some men compartmentalize relationships. They have someone for dating, someone for sex, someone else for the kind of love that leads to marriage. By being aware of the people in his life that he introduces you to and includes you with, you can get a good idea of how he operates in this area. Does he want you in all parts of his life, or is this a limited relationship? Love, in the deepest sense, includes sharing all parts of ourselves with another.
It is helpful to keep a little journal of your relationship. So many acts and expressions of love go unnoticed and unfelt, because we simply get used to them or become too busy to stop and take note -- or to stop and say thank-you. Take a few minutes each evening to note what you received that day, and also what you gave. Write it down. Be specific. List everything, like phone calls, kind words, a surprise visit, etc. You'll be amazed when you look back and realize all the ways your partner is giving to you. Plus, it'll help you find new ways to give back to him.