Why does he text me if he has a girlfriend?

I have a male friend that I text with. Sometimes many times a day, sometimes just a few times. Sometimes we call. We've been doing this for over a year now... anyways, I recently found out he has a girlfriend - that I wasn't aware of. Yet we still text daily. I can't figure out why and how we can be like this when he has a girlfriend. He claims not to have feelings for me... can we really just be friends like this? Do guys text their female friends daily? any insight, guys? girls?