When someone loves you, you should feel it. You should know it and never have to second guess or question it. Love has to do with actions not words. Merely saying "I Love You" really does not mean anything. They are just words that anyone can utter and have no meaning behind them.
So what actions do you consider to be a showing of love. This is where people often get a little confused. Does someone buying you the one item you desired most mean they love you? Not necessarily, it really depends on the motive behind them buying it. Does marrying you mean a person loves you? Not necessarily, it may just mean they wanted to get married by a certain time and they find you compatible and can deal you for the long haul.
When a person loves you it is genuine and pure. When a person takes the time to know you to the core that is generally a true indicator of love. When that person is so attentive to you that even when you don't see the fall coming they are there to catch you. When part of their happiness is based on your happiness. When giving is more important than receiving.
Love is such a basic concept yet is probably one of the hardest things for people to do in its correct form. When you evaluate who you love is it really love? When you evaluate who you think loves you is it really love?