What Causes Penis To Become Limp While Having Sex Before Ejaculation?

Hello Doctor, This might take a while, 3 year ago i lost my girlfriend and her dad in a car accident, since then i have worked 6 day's a week, 14 to 16 hours a day and got drunk on sunday,prob so as i would be to tired, or to drunk to deal with it, now i've met some one, a few months ago and we decided to have sex, the first 10 min is ok then the penis goes semi limp, so haven't ejuclated, this has never happend, I don't know if I'm just out of pratice, or it's somthing else, I'am 38 years old ,extremly fit have been a karate instructor for 18 years, eat all the right foods, have never smoked, only have a bottle of wine once a week with a meal now, have never had to go to a doctor, and would find this very embarrising if i have to. any advice would greatly received,