If you feel your life is drab compared to their lifestyle, you may find yourself losing interest in the things that brought you joy prior to your relationship. This could be a warning sign that you have made your partner responsible for all your social needs. It's quite possible that you will expect them to meet all your emotional needs as well. In time it will put a strain on the relationship. Especially if you feel being with that person gives you status or value.
Most people know when they are being used.
Some people try to base a relationship on it. The majority of those relationships are fraught with conflict and are often volatile. You might feel so lucky they picked you that you live in fear it will end someday. If your love relationship does not feel mutual, there will always be an unfair use of power. This can lead to abuse, exploitation, or at the very least, poor self esteem and emotional dependence.