Why is so hard to make friends when your older? everyone has that one friend they can call all the time?

the thing is i'm not very good talking with girls so I never dated..i've had chances but that ship has sailed a long time ago. to make things worse i don't have any guy friends and i know most couple meet through friends...I recently transferred to a uni and I dont' have any friends...i tried a few clubs and didn't like it...everyone that's not a freshmen doesn't seem open to making friends..this is a commuter school so a lot of people go with their friends...i even seen couples the first week so that tells you they knew eachother even before...I msg'd people ont his website bec. ..it seems soo many people are taken...i read there was a study and it said i believe 75 percent people are taken at my age (early 20s)