lasting too long ?

I know this probably sounds weird but recently my man and I have been bumping heads for a weird reason. He lasts too long in bed... for example. We can be having sex and I'll cum about 3-5 times depending on how good the sex is and during that whole time he won't cum at all... even when I give him head ... I'll be doing it for an hour or more straight and he won't cum. I try everything possible to try and get him to cum cause after a while you obviously get tired and or get locked jaw😭 I ask him if it's me and if there's anything I can do to improve and he just says "no babe I just know sometimes I'm not gonna cum quick and it's gonna take me a while.... it's exhausting and frustrating😩  I love him but I mean would any of you suck dick for an hour or more straight ? I need tips and or advice 😭