My friend's girlfriend is trying to seduce me what should i do?

he's a really good friend of mine and im not bragging but i know im a nice guy and i don't wanna betray my friend and i dont like tat chick ethir she may be the hottest girl in my collge but my gf is the only girl in my eyes and my friends gf is really nice too she told me tat she love me and i was like wtf she help me alot on my essays and she just really nice so tats why i cant push her away it'll just make me seem like a lowlife its not tat i didint try it before but when i try she started crying and i was trying to calm her down then she just ran away so i though wat was i suppose to do plz help.