Hi & Welcome.
I have gone through your query.
Delayed period could be due to
hormonal imbalance, stress, emotional disturbances, infection, any medical illness or
pregnancy.
Since your partner took I pill within 3 hrs following the unprotected penetrative sex, there are 10% chances of her becoming pregnant.
This is because the emergency
contraceptive pills like I pill is 90% effective in preventing pregnancy if taken within 72 hrs following unprotected sex.
My advice is get the pregnancy test done on the urine sample, if it is positive and if she does not wish to continue her pregnancy she must consult a gynecologist for probable use of pills like Mifepristone and
Misoprostol provide her pregnancy should be intrauterine (within the womb) and should be less than 7 weeks duration.
If the pregnancy test is negative the gynecologist will prescribe her
Norethisterone to induce bleeding.
Hope the suggestion given above could be helpful in getting the problem solved.