What is this guys deal?

So, I am 30 years old and have a friend at the gym who is the same age. We have flirted for about a year on and off. He who recently asked me to come workout with him in the mornings, hes teaching me how to use some equipment which is genuinely helpful.

To give you some context, I am a very attractive, fit women. I am very popular with men. We have so much fun at the gym and get on like a house on fire. What bothers me is that this guy flirts with me, and goes through phases where he messages me and is quite direct with his flirting.

I KNOW this guy is not dating material and hes super inconsistent. So this post isnt to ask if I should hook up with him. But I’m so frustrated at how inconsistent he is, especially when I’m used to men throwing themselves at me.

Can anyone give me any ideas to why this guy is going hot and cold on me?!?!