Still trying to put all the load on her because you're 'sad' you don't get to keep squirting away guilt free. Suggesting more contraceptive methods to her is not on. FFS. 'Depo sounds promising', but you're not the one who'll use it. And here's a little side note: they downplay the side effects to women all the time and women are conditioned to accept horrific side effects. They hard sell LARC and if it doesn't work for you they do not want to pull it out (coils and implants) because these things cost money.
I had a Mirena. Ten months of constant bleeding, horrible skin, mood sunk like the Titanic and took my libido with it. It was great birth control! I didn't want sex.
The copper coil, same thing, constant bleeding with heavy bleeding in between. Great for the sex life!
You say you can't live without sex. Well, side effects from some of this shit might mean you will be.
Female sterilisation, most trusts will no longer fund this. It's way more expensive than vasectomy.
So condoms combined with natural family planning. That is the only thing you should be suggesting to her, not what else she can put into her body so you can keep on as usual. And a serious discussion about what will happen if she gets pregnant again. A man who doesn't want more kids uses a condom or has the snip.
Personally if someone told me they expected me to be responsible for contraception because they might want kids with someone else I'd not think too highly of him, tbh.