Why? India have ToT and production jobs invested in Rafale. Singapore are far less invested in the F-35. Singapore is only a Security Cooperative Participant, not a funder.As a partner, Singapore is a sure-in. That's not the case with countries like Korea and Japan, which are actual exports.
Comparison with India would be the FGFA, not Rafale.
Lockheed Martin F-35 Lightning II - Wikipedia
Singapore and the F-35B Joint Strike Fighter
Singapore joined the F-35 program in February 2003 as a Security Cooperative Participant (SCP). As an SCP, Singapore is believed to be able explore configurations of the JSF to meet its unique operational needs and form its own program office.
Hasn't India done the same with the Rafale?