Handjob advice

My boyfriend and I have been taking it slow but he finally fingered me last night and it was great but when i went to give him a handjob he told me he had never came when a girl has given him one before and that I still could but I should know he wouldn't come.. (I gave him one and he said he was close but he never came like he said) it seemed very odd to me and I am wondering if anyone has an idea of why he never has. He is 19 and I am 18.