General

Gf don't want to gain

You're just 20? Life is not running away from you; there is plenty of time.

Priorities in a relationship.... Say she would want to gain for you, you marry, it's 10 years later and she gets an illness through which is loses and should never regain. You'd split up?

Mine was a few lbs from 200, she knew by then that I like her fat(ter), and one Christmas for my present i just asked for her to be AT LEAST 200 lbs. She gave me that and as weight comes on easily but is hard to get rid off she's now between 214-219, with more to come
4 years

Gf don't want to gain

If you don't want to be outside of a feedee relatonship, you need to be honest with every woman you date. The women should know that any relationship with you would require her to gain weight. And even then, there is no guarantee that she can or will keep the weight on and adding more.
4 years