can't finish when jacking off

luke....i sometimes struggle myself...u know all stars must be aligned just rite...many things can distract and cause the rite buttons to not trigger..........personally and i have seen many here agree...if foreplay last tooo long...numb dick steps in and delays the trigger...if i want to get a NUT...do it with vigor and do not stop/edge...get on with it...same w/intercouse sex...if I want a cum inside wife...take first feeling of no return..it may not re-occur....good luck..if u find a rememdy..please share.
 
It may be due to slight pressure infront of others - you can relax more on your own. I'd probably feel slightly inhibited too.

Other things can be a problem - medication, or loss of sensation due to age, etc - but since you manage when you're on your own, then that probably isn't an issue.
 
You're putting too much pressure on yourself, definitely. Try to direct every bit of your mental energy to the head of your cock. Make it the only thing you're thinking about. and don't hammer hard on your cock = gentle and well lubed is best.

I've had that happen before - too much pressure can indeed spoil your performance. Sex isn't easy, oddly enough. Takes some mental energy. And it can go wrong.

Just think calm, and think only about your cock, and how it feels right now. Don't make orgasm your goal, and maybe one will sneak up on you.