The main risk is double the change fees should you need to cancel or reschedule the trip.
Another strategy would be to have your wife book 2 RTs and you 2 RTs (or 1 + 3 RTs) so that the outbound and return are on the same record. Downside of that is that not all pax will be on the same record in case there are IRROPS.
Note that you get a stopover and open jaw on a RT itinerary, so you may want to use the RT approach if you want to take advantage of that.