https://www.macrotrends.net/stocks/charts/JBLU/jetblue-airwa...
https://www.macrotrends.net/stocks/charts/SAVE/spirit-airlin...
I am not an expert in airlines, and I am sure there are COVID effects, but it seems like the other domestic airlines have bounced back quicker since they are showing profits.
But more importantly, I remember Jetblue wanting to provide a better than average flying experience when the airline started, so I presume the only reason they would want to merge with Spirit, a company who does the exact opposite, is because they are facing financial headwinds.