Import -> Import gets fail on Updating Spouse relationship status From Blank to Spouse

Company - City of durham for hspl
1)Login with partner
2)Select company -> Create spouse template
3)In Data For Spouse Relationship status given as "~"
4)Import the file -> Import done successfully
5)Update the spouse relationship status from ~ to Spouse
6)Import gets fail

Note In DTS Spouse relationship is passed as Null
PFA