Because living is not about puritanical dedication to some ideal, it’s about living the best life you can. That involves compromise. It involves choices where there is no clear best path. It involves leaps of faith and taking risks.
If you want a proscribed, ethically pure existence, there are many variations on monks and nuns, of many different dogmas. But unless you are prepared to subscribe solely to a dogma, then by all means aspire to high ideals, but give yourself a break if you do not always attain them.
Living isn’t about reaching some perfect ethical Nirvana. It’s not a race to see who can get the best report card from God/Yarweh/Bill Hicks. It’s about the journey. It’s about the mistakes and lessons learned. It’s about finding your own path and your own balance.
If you do not bend with the wind of your life, you might find that it breaks you. Give yourself permission to let that halo slip once in a while. Maybe even forgive others their slips too?