To me the biggest thing that doesn"t make any sense is the purse being on the roof of the car. Let"s assume it"s a four door car, and wifey was going to put the kid intheir kiddy seat in the back, side of the car is mostly irrelevant. Cousin is sitting in car (that"s what I gather from Galiem"s story), most likely shotgun. So wifey approaches a back door for the car, opens it, and decides "jeez my purse is in the way." Instead of doing the intelligent thing and handing it to the cousin, dumping it over the front seat into the driver"s seat, or putting it down in the back seat, she puts it on the roof. The best assumption would be that the purse ends up pretty much directly over the door wifey is now standing at, bent over fucking around with a child seat. Said purse would be almost directly over her head.
Depending on what kind of vehicle you drive, chances are the purse had to be taken from thesame location wifey was standing at. At the very least the same side of the car. I"m no giant at 5"9", but when I towel dry my car I can only reach maybe 2/3 of the way across my car, and even then that"s awkward. Unless the thief was also extremely tall along with being fucking invisible, they"d not be able to get at the purse from the other side of the car. And now that I think about it, if they did, your wife would have to be completely blind to have not seen them anyway (as she"d be looking at least partially in that direction while she was leaned into the car).
So basically, the thief had to sneak up directly behind your wife to take the purse, without her noticing. On top of that, your kid didn"t make any sort of reaction (no idea how old they are) even though they"d probably be looking at mommy, and hence at the direction the theif would be coming from.
On top of that, your cousin is also in the car, and managed to not see anyone sneak up behind your wife and take the purse and magically disapear.
None of this makes any sense man. I"d honestly question the wife about it and see if you spot inconsistencies, something doesn"t make sense.