I have been dating one of my friends for about a month, and it's getting to the crossroads of the relationship. We have had a few dates - I made him dinner, he made me dinner, we went out with friends... the norm. I am getting the feeling that he is getting weird about the sexuality that has been incorporated into the equation. I don't want to scare him away, but at the same time, I don't want him never to talk to me again. We all have the same mutual friends, so when he unexpectedly shows up where I am, he acts weird, and doesn't "notice" me. I know that he wants to take it slow, but is there anything that I can do to ensure him that I am serious? Will that scare a guy? What about calling him?

You mean you to are having sex, but he does not consider you two a couple?
First you need to stop having sex with him, if that is what you're doing and then ask him how he feels about the relationship you two have developed.
And then maybe all he wanted was the sex and now all he wants is the friendship back. Don't worry about scaring him off, worry about your concerns and feelings.

Your thought of being at a crossroad in a relationship that has been in existence for maybe 30 earth days would not just make me act weird but would turn me into a solid lump of coal. He's still working through the basic stuff that comes with feeling strongly about a girl. Things will be fine, just give him time to come to his senses.

Even though you are friends it doesn't mean you know each other well enough to rush into the next level. He isn't ready, or is inexperienced, or worse . To late to go slow as the train has already sped down the track. Talk honestly to him but be ready for his honest answer. I don't think he is interested .