It certainly isn't anything that I would get involved in but it isn't illegal....go for it. But you have to remember that it's a fact that men mature SLOWER than girls. Google it. Also, the frontal lobe part of the brain doesn't fully develop until one is 20-25years old. They're still growing and developing. The frontal lobe of the brain controls rational and irrational thinking and behaviors, as well as it carries permanent parts of the personality traits. This means that his personality can and will change someday when the brain is fully developed.
Also, you have to understand that a 19 yr old just reached adulthood and is barely into college. They are technically still a teenager. Their life isn't very independent yet and usually the parents are still providing a lot of financial support. A 19 yr old hasn't reached 21 yet, and therefore hasnt experienced partying and the self control that is involved when you have a real I.D. and responsibilities/obligations.
I dont think its wise
to get involved with someone so life-inexperienced and developmentally immature, but it's your life and you can do as you wish. A relationship will likely not last because what 19 yr old is selfless enough to care for your emotional needs and what 19 yr old boy wants to be with only one woman for the rest of his life? None. They want to experience tons more vageen just like yours. If he hasn't realized his appeal yet because he's shy, he will notice it soon once he sees how an older woman is digging him and what else he can do with it..
If you're also immature for your age, then maybe the relationship has a chance. If you're fine doing nothing progressive (like living together/house buying, financial stability, engagement/marriage, kids) for at least 10years, go for it. You'll be waiting a long time for a young boy.