He struggles to tell her.
At first, it's because he's stunned into silence by the prospect of her moving all the way to England. It feels like she's doused him in ice cold water, when two seconds before, being this close to her was burning him up inside (in the best way possible).
And he won't tell her. Not if she thinks for a second it's only in response to what she might be doing.
He becomes too busy to tell her.
Dealing with another super-villain, this one with powers that even he can't compete with (and his mind jumps to Oscorp again, of course it does). He has to save all the people in Times Square, and he can't afford any mistakes right now. Not when the mood of Max hangs right on the balance between stable and crazy.
And he can't tell her then. Not when his limbs are stinging, not when she's staring at him with those eyes that he can never quite read.
His life becomes too insane to tell her.
Harry Osborn, his best pal from childhood, the person that was there for him when nobody else knew what he needed. He was only a child, he couldn't grieve like his Aunt and Uncle were. His best friend is dying, and Spider-man could save him. Or Spider-man could cause even more pain and suffering.
And he doesn't tell her then. Not in that store cupboard, not when she's freaking about Max. But he tries - not with his words, he's never been so good with those (god knows it was sheer luck that the "but those are the best kind" line came to him when it did). He uses his lips for other things, but then life gets in the way. He needs to keep Gwen out of trouble.
He becomes too wrapped up in his past to tell her.
This image of his father, the scientist who was always so vague and so secretive. The scientist who started this research but for whatever reason, ran away from it. And he's always doubted what Dr Connors had said, but hearing it out of his aunt's life... well that just makes it more real.
And he won't tell her then. He builds up to it, of course he does. He rambles on about Harry and vaguely about his father, but as soon as he gets to "the one thing" - he realises where they are. And he bottles it. Even when she's telling him that they're on different paths and that she has to go.
He thinks about himself too much to tell her.
He's just found out this massive secret from his father's life. A truth that could change everything about how he's been living his life, could cause biological weapons to be created in his father's name again, could even be manipulated to save Harry's life.
And he's missed out on his chance to tell her. She got in, of course she did. She got in, and she's on her way right now, and he's never going to see her again.
He knows it's now or never and tells her.
He loves her. He loves her more than he's ever loved anything, more than he will ever love anything. He just forgot for a while. He let her father's death shadow everything, let her father's desire for her safety and his adamance that he wasn't going to be safe for her eclipse his heart and what he wanted, but as soon as he heard her voice on the phone, asking to meet. As soon as he saw her standing there, everything became clear. And yes, everything got crazy for a while, and yes, his father's history is never going to really make sense if he follows her to London, and yes, there are going to be villains here and Harry's going to get sick but none of that matters.
For the first time in a long time, probably since he walked into that classroom and saw her seated there and went against his promise to a dead man for the first time... he's being reckless.
"You're my path."