Ditto, I have talked about this with my wife. Her concerns are that our relationship which is fantastic will change. Just curious if anything changed for the better or worse with your significant other?
If the idea of her taking two cocks at once is appealing but the thought of involving another Human is the hold-back, you might want to consider alternatives.
Perhaps a sex machine and various sized dildos to simulate spitroast, DP or airtight would be enough to satisfy both your current desires and still give you sufficient time to truly consider whether that is enough or is more wanted/needed without the potential involvement of another.
Once you bring someone else into your relationship, everything changes.
