If you have the chance to have sex on a date, take it. Women will excuse any number of flaws once you've ****ed them. Things they would have stupidly nitpicked before they just won't, or at least won't dump you immediately for it. Stick it to 'em when you get the chance.
Also, a 2nd date rejection? Bleh. I know it sucks but get used to it. Women will dump you after a 2nd date for any stupid reason. Maybe she told a friend about you, her friend went "he sounds boring" and so she dumped you. That, to a lot of women, is all it takes.