Hi there..This is my expereince after 3months of marriage..
I discovered there is one fundamental cause for me to cum too fast.
That is...I wasn't hard enough b4 penetration. My dick couldn't get inside without me either hammering the entrance like a battering ram or pumping my dick manually to make it sufficiently hard. These activities are akin to self-masturbation which makes my dick super-sensitive after I finally enter my wife. The fluids and the warmth inside jacks the sensitivity even further and voila..Premature ejeculation after 4-5 thrusts. I can't even stay still inside without struggling like mad.
So, if you find yourself not getting a good hard-on when you jump into the sack, do yourself and ur lover a favour, don't dick it, just use yer finger/mouth/foot(???)..Just kidding on the last bit. Stop masturbating, reduce yer lovemaking, eat more proteins especially arginine, massage ur pubic area excluding the dick with a traditional massaging oil, exercise more, take garlic supplements and most importantly make sure u ain't got diabetes. Plus it laso helps if u've stimulated ur lover good enough till she's wide open inside. Pumping away like a bunny upon penetration is not a good idea. Let ur dick adapt to vaginal environment and vice versa. Let go any notions of pornographic performance. Go slow. If you think u can up the throttle a bit, do so with control.
Hope that helps. Cheers