It's not that Turandot Does Not Like Men, it's that she's terrified of sexAnd why might this be? She's the Emperor's only child, with no mother in evidence - or even mentioned. What if, as a little girl, she saw her mother die in childbirth? Lo-u-Ling's tragedy was "thousands of years ago" even by Turandot's reckoning, yet she seems to attach some very real and present emotional issues to it. Her aria explains that she is very aware of being Lo-u-Ling reincarnated. If she really is, that's where she got the idea that Sex = Death, and by the third act she's full-on Sex Is Evil, and I Am Horny.
By killing herself, Liu transported her own soul into Turandot's bodyLiu could be seen as a full-blown Christ figure who dies to make the happy ending possible. It seems that her spirit of love does indeed resurrect... in Turandot herself. Only when she dies does Turandot defrost. The interpretation that Liu lives on in Turandot in more than a metaphorical sense also makes the Happy Ending less jarring, because the best character in the opera didn't die, she switched bodies, and managed to end up with the man she loved.