Oh no! The desire of a person passionately in love with another to fully convey the depth of their feelings persists to this day..
The experience of reading a handwritten letter exceeds the impact of the same message sent as an e-mail or text message which are essentially disposable and transitory media.
If you want to thrill your beloved with such a message but are afraid of making embarrassing errors, you can compose your rough drafts on a good word processor with spelling and grammar checking features. You then write the letter carefully in your own handwriting and then send that to your beloved. Use high quality, acid free paper and a fountain pen. It will enhance the final product.
Even writing out such a letter by hand will feel special to the writer and so much more so for the recipient.
Dare to do it!