Does distance make us distant

One of my husband's best friends moved this weekend. She had been living just around the corner but now she has moved about 45 minutes away. I wonder how easy it will be to keep in touch and whether the friendship will now change because of the distance.
Does distance make us distant?
I used to be in contact with women I worked with on a daily basis and when I lost my job we tried really hard to stay in touch....It worked for the first year, then it became less and less as time went on, yet we were inseperable at work, knowing what each of us was doing every day of the week.Were we really interested in each other or was it just to relieve the boredom of our everyday lives?
Are we only friends with people when it's convenient?
All relationships require some work...I must go, need to call a friend.