You: "Guess what babe!"
Santana: "What?"
You: "Sam proposed!"
Santana: "Oh... what did you say?"
You: "Yes, of course I said yes. I love him so much."
Santana wished it was her you loved.
You: "San what's up? Why are you crying?"
Santana: "Oh I-I'm just so happy for you and trouty mouth!"
Her smile was fake, her happiness was fake. She wished she told you how she felt, but rejection from you would be worse than anything.