The fact that Sherlock said 'I love you’ twice says so much 

 (Sherlock meta by yourpersonalintelligentelephant

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I think the fact that Sherlock said 'I love you’ twice says so much.

Let’s observe the way he reacts when she tells him she’s not an experiment. He is flustered as he says “No, I know you’re not an experiment! You’re my friend!” He is being the most sincere, I think, than he’s ever been with her. He’s so against the thought of her believing he only sees her as an experiment, that he doesn’t care for her at all that he must clarify that he’s not just trying to use her or manipulate her. This line, right here, is proof that he does not want to give her the wrong idea. That he wants to be truthful and honest and to not wreck the friendship they have. That he does not, in fact, want to manipulate or use her.

So if that is true, then why does he say he loves her twice? He is being backed into a corner and made to say it once even though he does not want to give her the wrong idea, but he does not have to say it again nor does he have to say it so emotionally. He is being 100% sincere when he says he loves her and if you think otherwise, then you have an awful understanding of the scene.

Of course, whether he means it platonically or romantically is up to you but I believe the way he breaks down and destroys the coffin is a clue that he is disappointed in himself for feeling the way he feels. He always thought romantic feelings were for boring, mundane people and I think the destruction of the coffin was him realizing he cannot deny what he feels anymore and that he can’t hide his feelings from himself any longer.

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