Don't get married for this kind of reason. Ever.
In the US (for example), it's considered to be fraud. I imagine in a lot of the world, you'd end up being deported and your boyfriend paying some fine. He might even have to serve jail time in some places.
And as for your relationship, this sounds like the premise for a lousy Lifetime movie.
Life ain't the movies.
Either get a job (and his help is of course a good thing) or don't. If he ends up engaged to someone else due to having to rush (I guess), then there's really no guarantee that that wouldn't happen even if you did get to stay in wherever he lives.
And if he is using that information as leverage over you to try to force you to stay, then that's a red flag that is so large it should block out the sun.
Benjamin Franklin said, Marry in haste, repent at leisure.
You have no idea how you can possibly get out of the marriage if it goes sour. Are the divorce laws skewed against women? Would a lawyer be super expensive? Breaking up when you're not married means you give back some stuff and part ways. Getting a divorce is a very, very different animal.
This has bad idea
written all over it.