Game Over—You Win
It’s pretty clear that this person, and perhaps even his girlfriend, are pretty hardcore Pokémon fans. Why else would someone go through all the trouble of creating a custom-made Pokémon card called Diamon with 150 HP with the passive skill of Will You Marry Me?
Yes, indeed, this is a Pokémon-themed proposal. If the girlfriend answered yes, then the card game was over. She would gain a husband who would be with her forever, and hopefully, they could spawn a bunch of children who would have the same love for Pokémon. This is probably the wrong thing to focus on, but this card doesn’t have any damage-dealing skills, though.