Bang! Like a thunderbolt, or in some cheesy film: you don't know what's going on at all. One minute you were blissfuly happy with your beloved, the next you meet someone who just bowls you over, makes your heart beat a hundred times faster and makes you lose all reason. All in a day, you're ready to throw it all away to follow him to the ends of the Earth (or maybe just to a rendezvous at a hotel round the corner). All because you can't resist the charms of a handsome, dark-eyed stranger. You can't explain it - it just happens.
OK, so the chemistry's definitely there...but do you really have feelings for him? Which is worst: having a quick fling, or falling in love with someone else? And make sure you know what you both want.