Let me tell you in a few words why i'm ok with the proposal
1. Sheldon simply had the ring already. It was with him all the time. He left Caltech and went straight to the airport. Dude was probably just waiting for the right moment.
2. Look at him while he’s holding that ring. Look at his face. There’s no doubt or dispair or insecurity there. Just certainty and calmness and love. His decision to cross the country to ask Amy to marry him wasn’t an act of despair, was an act of love.
There will be some drama. They will talk about it. They love each other. It will be fine.