OP,
Shorter high intensity group rides. Find a solid B ride and try to hang...say a 18 to 20 mph 30 mile ride.
If this becomes too easy and you yearn for more fitness find a A- ride which is my sweet spot...say a 30 mile ride with a 21 mph average which has a sprint in it and speeds can get to 25 if the group is getting frisky.
Next level is A or A+ rides replete with CAT racers. These are eat your young rides with attacks and dropping. When I was younger I was more for this.
A- riders can do sub 5 hour centuries when members of the group want to do a long ride together.

Most of us lack motivation to train hard by ourselves and why riding with good riders helps as a motivator.

My suggestion is if you want to get stronger, stay away from your 3 hr, 130watt rides and start doing intervals, shorter duration and higher intensity.

Good luck