What does it mean for a male colleague with a girlfriend to text me in the middle of the night?

I think he has a crush on you, but if someone with a girlfriend sends this kind of text message in the middle of the night, then his relationship with his girlfriend is definitely not very good, or you have done something to make him misunderstand. I don't think you should get involved. Even if you secretly love each other, since he can betray his current girlfriend, will he betray you later? I think you should take a stand, don't get yourself into trouble, and protect yourself.