The phrase, “the hottest love has the coldest end” has been around the block. It’s even featured in a Drake song. I just saw it on Facebook attributed, as it is most often elsewhere, to Socrates, but never with a specific source.
This seems suspiciously un-Socratic to me, so I started googling. In the 19th century a bunch of anthologies of quotations attribute it to Socrates (starting with an 1825 anthology by John Anliss), but again, never with a reference to an ancient source. The earliest I’ve been able to trace the quote (via this article) is to a 1587 novel by George Pettie, Petite Pallace of Pettie His Pleasure (apparently plagiarised by a contemporary, Robert Greene). Pettie writes, ‘the greatest flowe hath the soonest ebbe: the sorest tempest hath the most sodaine calm: the hottest love hath the coldest end: and of the deepest desire oftentimes ensueth the deadliest hate.’
I might be wrong, and someone who knows the Socratic traditions better than I can set me straight, but I would wager that this eventually got ascribed to Socrates because it sounds like something a wise person would say, and who could be wiser than Socrates? In the same way, we see today a myriad of apocryphal quotations ascribed to Lincoln or MLK. This is at least in part because attributing a quote to ‘George Pettie’ (who?) doesn’t carry the same gravitas.