its entropy...
And in Jerusalem, there is not as much to do "gay wise". You should take a short trip to Abu Ghosh and eat some hummus and felafel there, its the best, though I don't know the best places to go there.
There is a place called "shushan" on shushan st. near city hall, its a little place but it is interesting. Its owned by one of the city councilmen.
Apparently there is a new party called "Troy", on Hillel street but I don't know anything about it.
Jerusalem is not as much "fun" as TLV, but there are a lot of great restaurants, but I don't know them 'cause I don't spend much time there.