Every time we go out with this other couple, the guy gets out the calculator and computes how much each couple owes. I find this obnoxious. Whenever we go out with other couples, we just split the bill. They are nice but this is getting to the point I don't want to go out with them anymore.
Beat them to the punch. Tell them what they owe before they can compute it. If they push back, just tell them you are more comfortable just splitting the bill. If they persist, you need to disengage with them.