Sheena brought home a stray cat and wanted to keep it. Monty is super allergic to cats, but she insisted. He went through a procedure that would temporary make him more resistant to cat allergy, but something went wrong and he died from organ failures.
While he was sick/dying, Sheena set up a gofundme and received hundreds of thousands of dollar from fans. She kept the money after Monty died to buy breast implants and other things. Just one month after he died she was already dating a new guy.
Sheena and Monty married without anyone knowing, including Monty's family. This was apparently a manipulation from Sheena's side so that she could earn a green card in the US, plus get a good hold of his money.
Sheena quickly earned a reputation for being a bitchy gold digger. She tried to use her status as Monty's wife to get a foothold in RT. She acted like a queen, which people at RT secretly did not like.