Blowjobs

How come I've read a lot of blogs, articles on how to give the perfect blowjob and I've been doing them the right way but my boyfriend won't finish off. I've played with his balls, put them in my mouth, licked and deepthroated him but still nothing. He can't finish until he penetrates me... Am I bad at giving head? Lots of my ex lovers have finished off in an instant with my head game. Why does it not work on my current bf?