Premature Ejaculation is defined as ejaculating before you choose to. Guys (should) have control over the timing of ejaculation, you see.

I'm supposing that this hasn't been a problem all along, but is something that is 'episodic' - or something that has only recently transpired?

- Does he know that you would like for him to hold off ejaculating for a bit longer?

It could be due to miscommunication, you see, where he thinks that his timing is just fine.

- Is it a problem when he is controlling the pace / depth of thrusting or only when you are?

Guys can control when they ejaculate by controlling the pace / depth of thrusting - but if the female is controlling those things (and the guy isn't cuing what he needs) then the guy may well not be able to control when he ejaculates.

Some guys don't figure out how to control when they ejaculate naturally so there are techniques for teaching them how. It might be that he could benefit from learning these techniques whether or not this has been a problem all along - or that you could help him control the timing by employing these techniques when he cues you that he is about to ejaculate.

- The squeeze method is one technique (stop thrusting and squeeze below the head until the feeling passes and thrusting can resume)

- Stopping thrusting is another

- Diverting ones thoughts to something else is another (something he has to do)

There are also SSRI's (where the major side effect is delayed ejaculation) but why go there without trying the other techniques (given the other major side effects of SSRI's)?

Sounds like it might be best for you to talk to him about this...