From the 2nd chapter (The Fate): (Translated by Tauriel)
He was kissing her as if for the first time in life. As if for the last time. He couldn't imagine before that such thing was possible. That initial desire he had experienced in the first day was… No, not gone but utterly absorbed by another, more powerful feeling – like fire absorbed by fire. Now even this fire was replaced by a new, more powerful and pure flame. In this flame all the filth inside the human soul has been first revealed and then burnt out completely, without even ashes left. He could not make a name for this new fire but he saw it in Lúthien's eyes and he understood that he had been wrong all his life by giving this name to other things: the boyish obsession with the first call of awakening masculinity; the exiled loner's unspoken yearning for warmth and care; the admiration at the singing half-goddess and the call of flesh; the worship of the greatness of mind and soul… None of these disappeared but they have been cleansed, changed and took their own and not other's places in thoughts and in soul. Beren was reigned over by love, free and pure.
From Chapter 6:
On the Elf's open palm they were lying like gems, even with sort of facets on them – the berries grew so densely that some of them became flat on the sides.
‘They must be very sweet,’ said Aimenel softly. ‘I don’t know why, but these cherries seem sweet as never before… Take some, Rusco.’
Gili took half of the cool berries.
‘That’s because they’re first,’ he said.
‘My amilessë is Tinvel,’ said Aimenel suddenly. ‘Call me so, if you wish.’
May be considered also as a Tear Jerker because the reader will learn soon enough that they were the last cherries in boys' lives.