If you're looking for a meeting place or a good stop around ½ or halfway between Fort Wayne and Decatur, IN, you can try Hessen Cassel, IN, which is about 19 minutes southeast of Fort Wayne, or about half an hour northwest of Decatur, IN.
Another possible place to stop near the midpoint is Poe.
About ⅓ or a third of the way, you can stop at Eastland Gardens, IN. This is about 12 minutes southeast of Fort Wayne.
About ¾ or three fourths of the way, you can stop at Williams, IN. This is about half an hour southeast of Fort Wayne, or about 9 minutes north of Decatur, IN.
If you drive straight through without stopping at all, the total distance is 26 miles. The distances shown above don't include local roads to get into each town, so if you're planning a long road trip, make sure you factor in traffic and road conditions, rest stop breaks, and interesting detours along the way. If you're in a rush, you can do the trip with zero stops, and your total travel time would be around 40 minutes.