Hi,
It's great to hear that you are getting on well, and that your wife also wants to start too!
The short answer to this is that, yes, you can do it and it will work. The down side is the run log won't work much as it's not really supported. The long answer follows…
You're actually the second person to mention wanting to share the app in the last few days! I'd discounted the idea of adding formal support for this, but perhaps I was too hasty… If this feature keeps getting requested I'll have to rethink!
At the moment, Get Running remembers the runs you've done, and it assumes that all the runs have been done by one person. It looks at the most recent run in its log, and puts the little yellow running person after this to indicate the next run you'll be doing. The future run dates are also determined by the run log.
However, you can override the run that Get Running suggests you do next (the one that the running person is standing next to). All you need to do is select a different week and press the Run button. Get Running will check with you, asking if you really want to run the different run. Confirm you do, and it'll then coach you through that run.
So it is perfectly possible to jump about. The disadvantage is that the run log will then have both your wife's runs and your own runs in it, and the little yellow runner will jump about depending on which of you used it most recently. Also, the future run dates will be … probably a bit confused, frankly!
Provided you don't care about the log being crazy, you can go right ahead and do the runs.
It is also possible to delete runs from the log. So what you could do is reset the current log to clear out your runs, and let you wife use the application to log her runs. When _you_ go for a run, select your next run as described above. After your run, go in to the log and delete the run you've just added. This will mean that just your wife's runs are in the log, and Get Running will continue to function completely normally as far as she is concerned.
I hope that's clear – it's very long winded, sorry! Let me know if you've got any more questions, and all the best to you both
Happy Running,
Benjohn