saintlyjimjams: "Do people really not understand why someone might not be able to leave their children for a weekend"
I know. It's astonishing, isn't it? For a start, finding a babysitter is a huge extra expense when you're already paying a load of money for travel and hotel rooms.
Second, not everyone has a babysitter or relative they can leave their child with - at 18 months, we had never used a babysitter for DD and there was no way we would have just dumped her on a complete stranger for a whole weekend. It's your child, ffs - why would you make them stay with someone they don't know? And lots of people either don't have parents who are alive, who are nearby, or are physically well enough to look after a toddler.
Finally, and this is obviously weird of me, I liked my daughter. At 18 months, I would have found it hard to spend a day away from her, let alone a weekend. I'd have just fretted the whole time.
In the OP's case, I would let her DH go to the wedding and stay at home, but I wouldn't be very happy about it.