Vested share options clarity

Hi, my SO left her startup in Dec 2020 after only being there for 3-4 months. They offered her a vested share plan where she was given the option to buy shares in the company. A certain number of options vested starting March 2021 and she was given the opportunity to purchase 10,000 options @ .72 c per option (7.2k all together) and she, adhering to the advice of her dad, decided to purchase all the options and put down the 7.2k. Starting in March 2021 every 45 days, 625 options would vest, allowing her purchase them. She originally thought she had 90 days to purchase all the options, but what it seems to be is that after 90 days, the options roll back into the company and are unavailable to her. So is she really out $6,750 because of this? Unreal. I don’t see how the company would allow her to buy up to 10,000 but realistically she only had the opportunity to get 625 of them. Are we missing something? Thanks in advance.