Everything Tony has been thinking, everything he has been planning for this moment crumbles at the sight before him, and it terrifies him more than his own bomb landing in front of him, more than being operated on while still awake, more than anything they ever did to him in that cave.
All coherence vanishes, and Tony finds himself painfully stumbling through his words, because "I love you – and I'm dying" does not quite cut it. He does not want to force her hand if she believes him on either count and if she does not…he's not sure how he will handle Pepper's anger morphing into disbelief, or worse scorn: "Do you know how short life is…. and if I never got to express…And by the way, this is somewhat revelatory to me, and I don't care….I mean, I care, it would be nice, I'm not expecting you to ….to…. Look, here's what I'm trying to say, I'm just going to say it…"
When Pepper cuts him off to complain about the job he has passed her – and how he makes her life difficult, Tony feels the self-doubt well up within him; he's managed to make a mess of everything in his life – how could he ever be worthy of her reciprocating her feelings?
Then she notices the strawberries he brought her – a peace offering of sorts – and for a second he hopes, until it turns out that it's absolutely the worst thing he could have brought her, and he finds himself wondering if "Irony Man" might have been a better name for him.
Still, he wants to tell her this much before it's too late, he wants to do this right and not make her find out via some posthumous recording, so hope flares anew in him when Pepper says in a significantly calmer tone "I need you…" and leaping at the opportunity, he cuts in:
"I need you too, that's what I'm trying to say."
Pepper finishes her statement: "to leave. Now." and for the first time in his life, Tony cannot think of anything to say to that. He cannot find the strength to salvage his pride by saying something witty, and he's tired of trying for the truth.
The silence is heavy, oppressive, and without another word, Pepper starts packing to leave. As she gets up to walk past him, Tony grabs her wrist, aware that he's begging her to listen. He takes a calming breath then presses ahead; after all, she already probably cannot think any less of him, and there is no-one else there to witness his moment of vulnerability:
"Pepper, please, I l…"
This time it is Pepper who cuts him off, her tone angry:
"Mr. Stark, I don't have time right now for your antics. That will be all.".
She pulls her hand away and storms out, and this time Tony does not try to stop her. He's vaguely aware of Natalie – Natasha actually- looking in at him from the door before it closes, and he vaguely wonders if it is concern or anger on her features, but somehow he cannot bring himself to care.
It almost feels like he is back on his living room sofa, paralyzed by the sonic taser while Stane is ripping out his arc-reactor…. but this is worse, because this time it is his heart that has been ripped out -metaphorically- and this time he does not have a reason to try to save himself.
Eventually SHIELD's goon squad shows up and takes him home, telling him he needs to get to work, but he honestly at this point does not care, and nightfall finds him standing in his wrecked living room staring blankly out at the sea.