Look, realistically, a lot of people who adopt, or who consider adoption seriously, come to it after failed fertility treatment, so it's not that it's not a 'consolation prize', or that many people who adopt probably wouldn't have adopted had their been able to have biological children. That's why adoption agencies often stipulate a minimum period between the end of fertility treatment and starting the adoption assessment process, to give time to grieve and put the idea of biological children behind you. Because it's messy and complicated for a lot of people.
It's also why they stipulate using contraception, so that they don't spend money and resources on assessing adopters, only to have them drop out at a late stage because they've conceived.
But adoption is something both people have to be absolutely on board with. You will be probed and questioned in a very detailed way, and no one with reservations will make it through the first hurdles.
You can't make someone want this, and even if you were able to persuade your partner to go through the motions convincingly enough to get through the process, it would be a real trainwreck when you landed at home with a small, confused, challenging child.
See if you can find specialist counselling. And be kind to yourself. This is really hard.