chayav – no amount of dating can really let you ‘know’ the person before you actually get married to them and live with them. However, if they like each other well enough and they feel that they are capable of moving together in the same direction towards the same goals in life and raising a family, that is easily knowable by the third date. I was recently reading an anecdote from a book by a well-known rebetzen where she talks of a couple that had been happily dating for two years, yet as soon as they married their relationship went downhill.
The real fools are those who think that dating needs to take a long time for them to know if this is the right person for them to marry – if all the correct research is done beforehand, it doesn’t really need to drag out.