Breaking news! Doctors have classified the infamous, so-called "Nisekoiphobia" as a very serious mental disorder. Patients have been observed to cringe and commit self-harm at the thoughts of a harem protagonist having to choose his "destined one" but not knowing which girl it is.
"Oh God no, don't pull a Nisekoi on us again..." Said one unfortunate victim.
The medical authorities advice to keep them away from any keys, locks, diaries, photos, or basically any sharp obejct. Nisekoiphobia is very infective and there has been no cure, having the only known vaccine is to not watch Nisekoi in the first place.
Proceed with caution.