Every weekend I do a ride with my friends. Usually this is a 6hr ride with a lot of short, steep climbs. I follow a plan and I try to get this ride to fit 
. My friends seem to get better every week by doing these long hard rides, I’m getting worse. Last month I was towing them home in the last hour. This week I was dead with two hours to go.
Anyone having similar experiences? Should I drop this ride and just do long slow rides combined with the plan (intervals) I am doing?
Are you just adding this ride to your plan without making any accommodation?
One possibility is that you are over-training.
@MatthiasC Also how is your on bike fueling and hydration? That is a very long ride and you can easily get in the hole on calories if you are not eating at the right times and the correct macros.
@Heretic I do less systm workouts to make place for this workout.
@JSampson calorie intake (waffles, gels) is ok I think, hydration can be a lot better for sure.
I am used to getting dropped on some hills, but I should always be able to keep going and do my turns on the flats. Now it’s like a dead pigeon.
Last couple of weeks not a lot of time to do my stretching (tight hips, hamstrings, lower back) but i don’t think this is the reason.
I would definitely check my hydration as @JSampson noted.
The disturbing part is that you say you are getting worse. If better hydration, or doing a few weeks of reduced workouts does not help, I would get a medical checkup.