Hi tr_gc,
Even though your SL date may be same as with your friend, your DC date may be different but close to your friend's DC date. As the processing of visa depends on Dc dates, your application may be processed at a different time. Just wait for a week or so, i am sure you will be approved soon.
I don't think applying with spouse passport delays the processing.
Good luck. Let us know when you get your approval.