Here's that question

Sure, a youngun can fall in love. Whether or not they are able to do the necessary work to sustain that love and help it grow into a healthy relationship is another matter -- but this is true of everyone, at any age. I think that in the teenage and early-twenties years, people are perhaps less motivated to settle down, and more easily distracted by other activities and other love interests. Of course, in some communities (religious sects such as the Amish, Mennonites or FLDS), there is less distraction and more cultural pressure to settle down (and therefore "fall in love") at an earlier age...

Rudecherub's comment on Yaria's answer defines love like this: "You love and give to another without demanding, expecting, or requesting anything in return for your self sacrifice."..
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That's very idealistic.....but is it realistic?..
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By Rudecherub's definition, forget 19 and 20 year olds -- how many people of any age can truly fall in love?..
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Either way, I'm with Yaria on this one. ..
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I'm guessing that love will feel different at different ages, but I doubt that just because someone has more experience of the world at 35 then their love is true and mine is false...

The same could be said about someone in their 30s or 40s. Who really knows what love is? No one I've talked to seems to be able to explain it very well. ..
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My personal opinion is that you know what love is when you find it, and you can find it at any age...

it doesn't have a lot to do with age, in my opinion...i was engaged when i was 19, and it was true love... the problem was our levels of maturity...neither of us could handle the idea of a long-term commitment, so we broke it off...that doesn't mean that a person that young can't feel love, or even make a marriage work...as long as both parties are mature and have sufficient experience with members of the opposite sex, yeah...

Generally love begins with 'limmerance' a period of heady infatuation. This can last a few days, week, and months, what happens next is matter of choice, regardless of age...A person chooses to love...
At 20 I had no intention to settle down...I suspect this is true for many young people...
Also many people think love isn't a choice but something you just feel, so at the first emotional hurdle they bail and look for someone new. This isn't uniquely a fault of youth, but the pressures to couple are less at this stage in life...