Sometimes, no deal is better than a bad one—or so Kosmos Energy seems to think. The U.S. oil and gas firm abruptly called it quits on its potential takeover of West Africa-focused Tullow Oil, sending Tullow’s shares into a 10% tailspin on Tuesday. Kosmos didn’t offer up a reason, but “challenging” seems to be the word of the day: operational overlaps, debt-heavy balance sheets, and the ever-delicate dance with the Ghanaian government likely threw a wrench in the works. Had the two companies tied the knot, the combined…