I've found once you break a spoke, the sudden stress put on the rest of the spokes often cause them to fail soon as well. My rule of thumb is if I break a spoke, I'll replace it. If it holds, great. If I break a second spoke on the same wheel, then the wheel gets re-laced/replaced. Otherwise I'm just going to keep breaking spokes on that wheel.

Generally the stock wheels on bikes are machine built and while they may look true the spoke tension isn't optimum all the way around the wheel. As someone else mentioned, getting a hand built wheel from someone who knows what they're doing will usually put an end to spokes breaking. At 188 lbs you're not expecting a wheel to hold too much weight.