Well Ann may have tried. Barack Sr. knew he was already married, and could not legally marry her in the US. He also left them very shortly after Barack Jr. was born, whereever that was. He was just a predator, 7 years older than Ann, who knew he'd be going back to his wife, and probably taking other wives, which he eventually did. But I guess Ann gave him a taste for the exotic (by Kenyan standards) , since the wife after her, the second legal wife, (in Kenya), was also a white gal named Ruth who also eventually divorced him and married a Tanzanian.
Careful! A logical conclusion from that is that they went where he knew they could legally get married...
Dangerous turf. That could put pregnant Stanley Ann in Kenya.