Skipping period

hi if my girl misses her period and so far its 8 days late but shes been sexually active for a few weeks before that with me can that cause her to miss her period or what?????? please help

periods can vbe irregular people!!how many times must I stress this.and you all need to chill..before you start going crazy aboput potential pregnancys god damn it!!!lol.no seriously dont think too much of it wait it out if she dosent get it in 2 wekks.....maybe even next month depends how long youm can wait.....get a pregnancy test.I doubt she got knocked up tho.
-v-