Also, reading Nick's quotes, there are a couple of things that I think may have "set him off"...
His quote: she said "stop right here," it quoted Holbert as saying. "So I stopped and she said, 'I'll walk home.' I said, 'Are you sure?' She said, 'Yeah.' I said I figured she didn't want me to know where she lived, or somebody was there and she didn't want to be seen together."
Nick may have been ticked off that Kelli was texting somebody else all night while she was with him. Also, Nick "figured that Kelli didn't want me to know where she lived" or "somebody was there and she didn't want to be seen together". when he supposedly dropped her off. Either way, it's not a boost to Nick's ego...
And if Nick sensed from Kelli that "somebody was there and she didn't want to be seen together", that he would have inquired more about this??? Personally, if it were me dropping her off and there was a concern, I would have asked that she text me letting me know that "she is home safe"...
Isn't it strange that Nick thought about these things while dropping her off, but never questioned Kelli about her concerns at the time??