What Causes Delayed Periods After Having Non-penetrative Sex?

hello sir,am really confused whether my friend is pregnant.we did not have full intercourse.i just tried to insert my penis but did not succeed.is there any chance that she could get pregnant through my precum?her period is postponed by one week.so am worried.suppose if she is pregnant,how to detect it and what are the possible solutions for abortion?she is 21 years old and we dont want to have a baby at this point of time.
thank you.