...that Bingley had been in love before; and as other posts have mentioned, detecting people in love may not be Darcy's strong point. Darcy may have seen Bingley enjoy young ladies' company, esteem them, like them; but Darcy never tells us he heard Bingley claim to be in love, and since Bingley never says he was in love before, we cannot be sure Darcy is right. No doubt Bingley was as affable and engaging elsewhere as we see him in P&P, but more than that we do not know.