Is it wrong to be in love with an under-aged girl? Even to believe that you are made for each other and you can't imagine life without her? God has recently called me, and I'm leaving so much of what's in my life behind. I can't imagine a life without her. I see her in my future as my wife. But despite the fact that I truly love her, she isn't of age yet. Does this make it a sin?
I'm assuming that by love you are talking about the proper biblical concept of love as described in I Corinthians 13:4-8 and not the world's definition which involves sensuality and sex.
There is nothing wrong with loving someone, even if there are several years between your ages. Since she is under the age to get married, it means you must wait until the proper time. If you truly love her, it will be worth the wait. However, it isn't without risk. One reason there is an age limit on marriages is the recognition that a person isn't ready to make a mature decision. As she grows up, she might realize that you are not the type of person she wants to marry, or she might decide that she was blessed by God to find the right man so early in her life. That is something I cannot predict. But waiting for the right time is definitely not a sin.