Awkward situation

He tells me he loves me
When I don't feel anything
He tells me he wants to spend the rest of his life with me
How will I anwser?
I can't break his heart
But I can't stay with him either
How do I tell him, I am not interested
Without crushing him into pieces
Each day I see him
I feel so bad for him
Knowing how deeply he loves me
I can't bare to look at him
someday I will tell him
Just not today. .
He seems so happy
I don't want to break his heart
At least right now