Is it impossible for a marriage between a 21 and 39 year old to work?

I don’t think anything is impossible, especially when two people are in love. You do need to discuss your expectations for the future, given the math. So when she is 65, the general (but perhaps now meaningless) age for retirement, you will be 47 and could become the breadwinner. There are certainly bigger age gaps between couples, and many of those marriages work. But let your heart rule all. If you love her andare ready, go for it!

marriage is a 2 way street. it takes both of you, working together to make it work.

Only you two know your connection..as long as you have thought it over carefully as the age gap may not be an issue now but could it become one later..some have worked out so if you're happy and feel confident go for it! ☺

Life is uncertain.
Nobody marries thinking 'This might last five years'.
But the reality is that life is hard work.

If she's at the stage of thinking "Yay ! Finally !! Now we get to get a house ! Have six kids ! Dog ! Rabbit ! Mortgage ! holidays abroad ! Credit cards !
(eg: The life you were probably living 20 years ago)
You're gonna have a problem !

When wr got married I wes 32 and my wife was 74. She was my other half. A partner in every sense of the word.

Not impossible. Only the two of you know the dynamics of your specific relationship. It depends on what your future plans are, how in sync they are and how well you and she cooperate with each other.