Pretty sure what's happening here is that he just wants to be married for some reason, which is why he asked someone he barely knows and doesn't want to put any money or effort into the wedding.

He's not going to put any more effort into the marriage, either. This is not a real thing, this is him checking off a box.

You say he's a good person but you don't know who he really is. In part because you just met him and in part because he's been trying to convince you to marry him. (And even then he couldn't be bothered to get you a Valentine's Day gift? This is him at his best, dude.)

He's not trying to get citizenship, is he? That's just the most obvious ulterior motive for going through the motions of a wedding.