I had half a mind to make a joke about the left boob being bigger.
As a man, vaginas all the way.
Wait, that's not what you meant?
To finally be serious. I agree with Goafer, couples should have discussions about things affecting their future. Of course, the implant being nearly as simple to stop (just need to go and get it removed as opposed to not taking it) as the pill I don't see the big deal in this case. Him being drunk and perhaps her choice of words combined and made this into something larger than it ever was.
That said, an amusing anecdote about here in the States. A married man can not get a vasectomy without his wife being present for the consult and signing a piece of paper to allow it. A married woman can at any time go and have her tubes tied without ever even mentioning it to her husband much less him being present.