'Dumbledore was sure Riddle already knew how to make a Horcrux by the time he asked Slughorn about them...'

'Isn't there any way of putting yourself back together?' Ron asked.

'Yes'.... 'Remorse,' said Hermione. 'You've got to really feel what you've done. There's a footnote. Apparently the pain of it can destroy you. I can't see Voldemort attempting it, somehow, can you?'

**************************

perhaps when Harry said

'You're right. But before you try to kill me, I'd advise you to think about what you've done... think, and try for some remorse, Riddle...'

he wasn't trying to 'save Voldemort' - but to actually bring Voldemort to feeling pain enough to finish himself off.

Perhaps Harry wasn't trying to 'act the hero' this time....