I have re-read this forum and the opinions that he had a mental health breakdown are not my perception, in fact I see something different.
To preface this, the week prior to his disappearance we had two days of temps at 118/117 which can cause people to feel claustrophobic or grumpy. April and May were the only months students attended school and masks were mandated. Things were opening up. Grocery stores had arrows on the floors directing shoppers. People came out of the quarantine acting odd and feeling depressed. Daniel was probably a lot like the rest of us in that super weird experience.
Going through the DR there are all these indicators of a lucid, rational young man:
pg 15 he texted for permission to pick up the canopy he accidentally left, and was told to come by any time to get it.
pg 18: Luke didn’t observe any odd actions or statements the weekend prior to Daniel’s disappearance.
pg 23: Daniel showed up at the work site wearing his safety vest.
pg. 25: His FB post was the Suns in 4 referencing basketball.
pg 26: the common area of his apartment was “well kept and clean” and his bedroom was messy with clothes on the floor.
pg. 35: He ate, paid his bill and “packaged his food in a to-go box”
pg 38: according to Roger, Daniel spent a lot of money on computer parts.
unk pg: he left Tempe before 6:30 am to go to work, and took photos at the Verrado well site.
The fact that he worked two jobs, was building a computer which is sort of like a “hobby” and was following the Suns, and having conversations with people are all healthy emotional signs. His apartment description seems typical. Packaging his leftovers is a big tell that he was planning to eat it later.
I do agree that he seemed deeply hurt by the rejection due to his infatuation with K. Talking to friends and family, having a hobby, watching the Suns, and even his respectfulness in his text replies to K are indicators of responsible and healthy emotional responses. Of course, this is my humble opinion, and I am not a professional counselor or therapist.