You can't purchase a 10 day saver pass and use it for just you for 2 days and then the two of you use it for 8 days. This is because you would have to show passports for both names on the rail pass when you validate it before the first day of use.
From the section on Saver passes on this website, "Members of each pair or group must order the same pass together and all must be present to validate the pass in Europe."
On my trip to Germany and Austria last August, I did a lot of travel "off the beaten path". My six most expensive days of travel averaged less than €25/day (single). Only one day was more (€49) than €24. An eight day Saver pass for is almost €37/day/person (€75/day for two people).
For any day that you are traveling to small towns on regional trains, Austria and all German states (Länder) have passes which allow you on/off travel all day long on regional trains. Austria's Einfach Raus Ticket is €28 for 2-5 people. German Länder tickets are €26-€35 for 2-5 people, depending on the state; most are under €30.