I think this has little to do with the pandemic. A lot of casual dining establishments were struggling even before the pandemic. Chili's, Applebee's, TGI Friday's, and Ruby Tuesday were all good examples.
There's nothing that differentiates Ruby Tuesday from a lot of other places. No differentiation = bad in marketing.
Dinner dates have been declining over the past decade, but there are still too many unoriginal simps who take women on dinner dates within the first 3 dates before they've had sex.
However, I'll make the case that the bad mating environment is a contributing factor to the whole segment of casual dining declining, including Ruby Tuesday. While Ruby Tuesday is typically not a destination for an early stage dating, it would eventually enter the routine of established couples. Ruby Tuesday's business model is based upon established couples, often with children and often living in the suburbs, going for a meal in their casual environment. It has a basic menu with a lot of items and wide appeal. That's perfect for Mom, Dad, and the 2 kids. The problem is that with such a bad mating environment, there isn't as much demand for a place for the family and there's not demand for the suburbs. The Millennials aren't doing the whole home ownership in the suburbs and having kids thing as much as previous generations because they've been affected by 2 nasty economic depressions in 12 years. They don't have the money for houses. Even if they did, they are highly prone to layoffs, so why buy a house when you have layoff risk? Additionally, Millennials' romantic relationships are often as transient as their corporate employment. Unchecked female hypergamy is enabling women to have a large sexual buffet, a small percentage of men are getting the large buffet, a large percentage of men are thirsty simps with limited access to sex and they scavenge for it. This bad mating environment and fundamental familial structure change is why casual dining restaurants like Ruby Tuesday are restructuring significantly through bankruptcy proceedings.