limewave, it's good to have company for the longer rides but if there's nobody, we have a saying in Bulgarian: "The only soldier is still a soldier". So, don't worry about it and hit the road and trails. Two weekends ago I did a 6-hour ride only on trails alone, too.
This weekend I did a looong ride on road. It was a 130-mile brevet and it took me about 10 hours and 8 of them were on the saddle. Here I am . I did them on my bike with 1,9" tires. There was a strong head wind in the last 50 miles but we had to get back anyway. The last 5 miles I had issues with my gears and I was really upset because I had a XC race on Sunday and I didn't know what the problem was. Happily, my husband found out a crooked part in my chain and removed it. So I was ready for the Sunday's race.
On Sunday I was OK. The race was XCO and it was only 5 miles. I sprinted them in less than 30 min. I am happy with my training this week.