Isn’t a ‘too’ usually a very obligatory response ?

Isn’t a ‘too’ usually a very obligatory response ?
You are in the middle of something and your lover turns up with a i love you. Does your heart open wide with love? Or do you feel a sense of obligation to reply with an equally tender “I love you”?
Why not leave it with a simple thank you.
Does pleasing the other comes above being honest ?
How do you usually react to a Sudden “i love you” ?