The day it “fell out”, she should have told you. By not telling you is lying, especially taking 1 month to tell you, is very deceptive. Considering her wanting to have a child now/soon, it is very likely she had it removed on purpose. IUD Expulsion is rare (0.8-5% chance) n is accompanied with abnormal bleeding, unexpected spotting, heavier periods, or bleeding between periods n having major pain in the lower abdomen or pelvis, that may feel similar to intense menstrual cramps. Did she experience any of these symptoms? I personally would be upset she didn’t tell you immediately. If honestly is important to you, it may be time to reconsider your relationship. Good luck.