Is it normal? PLEASE HELP ME!!

Im a little weird out in one point! My boyfriend takes for ever to cum and still he doesn't have eyaculating problems, he can just deside if he wants to cum or not! I thought that it was maybe because he masturbates, but theres thetricky part he DOESN'T MASTURBATE!!!! 
​Is that normal? , is it good? 
​My boyfriend says that he can just deside that, but sometimes i dont like the fact that he desides not too cause then theres no fun!!  Please Help Me!!!