fauxpocrisy
The act of preaching against something, admitting defeat, and then partaking in that thing. Tends to occur when individuals are upset at a societal norm that is too difficult to change, but not difficult enough to pretend to be better than.
That girl who said she didn't want a diamond engagement ring because they were part of an expensive corporate-fabricated tradition based on blood diamonds, committed fauxpocrisy when she ended up getting and showing off her diamond engagement ring.