Cumming trouble

Stephanie
Okay so my boyfriend has trouble cumming while we have sex.
Alone with himself he is fine..but whenever we are together and sexual it will literally take hours or just not bother cumming at all.
Any tips on how I can help this problem .
He likes blowjobs but I mean I'm not a fan, I do it for him but any tips at all that guys like and really brings them to cum faster???
Helps a sister out