Should I get a new IUD with each new sexual partner?

I recently had an IUD inserted. I'm not currently having sex, but wanted to be prepared as I am seeing someone who I may become sexually involved with.

My concern is I was told the IUD would need to be removed if I had sex with a partner and then changed partners later. This IUD is a 5-year IUD and the cost was quite a bit. If I have sex now and then stop for a year (or any period of time) and was to become sexually involved again with another partner, why would it need to be removed? If STDs are not an issue, does it still need to be removed?


Do I have bulimia and will it interfere with my birth control pills?

Once a day, after meals — whenever my roommate isn't around, I stick my fingers down my throat and throw up most of the food that I had just eaten. I do not binge — I only purge. I understand from my Psychology professor that the diagnosis of bulimia nervosa requires that the person binge and then purge. I am curious, then, what I have — do I have a form of anorexia nervosa or what? Also, I am on birth control pills and I am afraid that I might hurt their effect by throwing up. How long does it take for the pill to get absorbed into my system? I usually don't throw up until about 5 or six hours after I have taken the pill. Will this hurt the effect of the pill?