How many MQMs does the Mrs. earn from flying every year? It doesn't sound like very much. It's unlikely Delta will continue to rollover all MQMs this year (they were just doing this during Covid and it's not a permanent thing). It might make sense to get own card if already earning 60K - 65K MQMs per year to get MQD Waiver and push over the top for Platinum status. But if flying less than 60K MQMs a year, the amount that would need to be spent on card (in addition to spend for annual fees) to hit Platinum status could just be put on a cashback card instead and Mrs. could use savings to pay for upgrades occasionally when flying solo.