Can single men have female friends?

I mean simply friends? I have had several male friends over time and I regretfully loose them one by one. Some have admitted to secretly harboring feelings. While others have just faded into the woodwork (especially after finding out that I got married). I really enjoyed their friendship and went to them for the male prospective when I needed one that was unbiased. Personally, I don't see any reason why our friendship could not continue. I understand that their interests may have changed. They may have changed. But I'm starting feel that it may be a male thing. Any men out there with an opinion on the matter?