My first recomendation is not to think of it as "psyching yourself out" and puting a negative spin on the situation. I would encourage you to see this as wonderfull new destination you're "going to" rather than "running from".
One of my realizations is that the fast is not just the physical feeling of well being but it is also an inner journey of awakening and getting control of your life. You really can not think of these "expectations" or anything else for that matter that deviaties from "your" journey and that is not to say that you should not acknowledge your significant others "expectations". Having read this far I'm sure you realize that there are ways to joyfully explain your doings/wishes to others in a positive light. Don't explain too much though or you will sound "preachy". Keep it short, simple and smile. It might surprise you how simple this really is and how understanding others will be.
The only "real" cravings will only last 3 or 4 days after that you're home free. You will get what I call "false cravings" which are really your desires for the sensual pleasure of eating. One simple way to deal with this is to just drink more lemonade or just plain water.
If the inner journey thing appeals to you at all then when you catch yourself having these cravings just shut down your internal dialog and self observe. If your internal dialog is still running you're not doing it right. This is a great opportunity for awakening/self awareness. It's no accident that most if not all religions and spiritual practices advocate some sort of fasting.
Have a great journey and see ya on the "other side".......