Started in Feb. with the Valentines Event (right on time to miss the Daily Quest Girl by 2 Days...). So far i got:

3/3 Dark Lord
3/3 Ninja Spy
3/3 Gruntt
3/3 Edwarda
0/3 Donatien
0/3 Silvanus
0/3 Bremen

+ most of the Event Girls (2 Drops, 1 Daily Quest missing). Having a really bad luck streak at the moment, 1 Drop (Festival Solveig) in ~6 weeks and over 500 battles since that drop without a new girl.

Looking at the numbers (occasionally i write down how many battles it takes for drop), it seems that with an increasing harem, the dropchance for a new girl actually decreases. Just horrible luck or are others having a similar experience ?