Hi, I'm a family lawyer and in the twenty odd years I've been practising I've issued petitions on everything from a husband who didn't pick up his socks (is there any other kind?) to one who attacked his wife with a claw hammer and puther in a coma for three weeks, and everything in between.
The court doesn't really care whose fault it is that the marriage has broken down, and usually it's down to both parties anyway.
Typically, you'll be expected to state the general background, eg saying that your husband drinks to excess/shouts at you/is secretive/wastes money/is mean with money, or whatever your main complaint is, then specify maybe 6 or 7 incidents to illustrate that behaviour.
so you may be saying that your dh is very unsociable and notinterested in spending time with you and the children because he's a workaholic or a golf fanatic. So you say that, then come up with 4 incidents in the last year where you've asked him to go on a day out with you and the children and he's refused, going to play golf with his friends instead.
Put enough allegations in that you can afford to prune off a few. The draft petition will be sent to your husband for his feedback and it helps to oil the wheels if he gets his way in having one or two of your allegations deleted before the petition is issued in court. If you don't agree the allegations before issuing the petition, there's likely to be an expensive and time consuming argument in court - far better to thrash it out before issuing.