On the subject of "cougar dreams" and older women pairing off with younger men, the concept did not originate with Demi Moore and Ashton Kutcher. Although the term "cougar" seemed to spring into the lexicon about 10 years after I could have qualified, I remember fondly a brief romance with a recent college grad of 23 who courted me when I was 29. Problem was, I couldn't stop humming Maggie May by (then still boyish) Rod Stewart and wondering when my boyfriend would need to be "back at school." As attractive as young gentlemen can be, it's nicer to be "honored" by men who are entirely grown up.
More importantly, sweet Samantha, you need not fear vanishing as you mature . In our youth, it is easy to be noticed but throughout life, the only people who really see us are the ones who love us. In your short 2 decades + change you have already accumulated quite a collection of admirers. To them and the many more you'll have, you'll always be three dimensional.
Personally, at your age, I looked forward to my post-youngster days when I'd have substance and could enjoy the fruits of my new ability to labor. My husband and I are almost exactly the same age. Now that we are indisputably un-young, I realize I may have been a bit too enthusiastic about my romantic plan of how he would "grow old along with me." Notwithstanding glowing affirmation that the best was yet to be, my life partner and husband of a quarter century, now as handsome as a grey wolf, has had to accommodate my weakening vision, failing hearing, and other reminders of organic wear. The good news is, to him, I am never, ever, invisible.