I don't think it's a good idea to get a puppy unless everyone in the household is 100% on board with it.
A puppy or dog is a huge commitment, you're right. Is he aware of just how much it will change your lives: no going out for the day on a whim, puppy won't be able to be left alone for some time, and adult dogs not more than 4 or 5 hours at a time, so no going away for the weekend without arranging care for the dog.
Puppies are babies. It will wake in the night and need to be taken out to wee and will possibly keep you awake at night at first.
Puppies need to be house trained and will need to be taken out every 20 minutes or so and after every meal.
And then there's all the other training that's needed.
Who is going to care for the puppy all day, and who is going to do all the training. Who is going to walk the dog every day, twice a day, even when it's raining or cold out? Is he going to do all this or is most of the care going to fall to you? If it is going to fall to you, he has no right to make the decision without your complete agreement.
You both need to know what you're letting yourselves in for. A dog can live for 15 years it's a long time if you don't want to do it in the first place.
Do some research and insist you make the decision together. And if you do buy a puppy, either try to get one from a rescue or research breeders. Be very careful you don't end up buying one from a puppy farm, which if he just goes out and buys one or answers an ad on the internet is probably where it will come from.