Yeah, I'm sure lots of people have lots of incomplete songs lying around. It's just not what we're discussing. The point is nobody else on the forum is pretending that they cannot make a judgment on the song merely because it lacks a second verse.
Everybody else who has commented on this thread has, in addition to correctly observing that the song is short and incomplete, expressed an opinion about the song's musical qualities which we all agree would remain the same if new verses were added since those verses would follow the same melody.
You ask: "If you have a melody to the 1st verse, and lyrics tend not to be the problem, why would you find it difficult to write a 2nd or 3rd?" Again, I wouldn't find this difficult. I haven't done it yet because, as I have stated: "I don't want to record it in its full format until I have the equipment, skills and knowledge of production as well as ideally a band rather than just myself with an acoustic guitar."
I think we may be going around in circles.
I'd be interested to hear what you think about the song. For example, since you think it's too short, do you think it is worth expanding?