Hi no problem! You can ask me anything. I answered "yes" to all his "you like what you see?" And I also went with Thomas to dinner ever night. I don't think the dinner thing affects the other routes. (Around Day 14 or 15 there's one scene during dinner time that revolves around Kevin. I think it's vital for the route's progression too. Choose "prank" to do this) Make sure to save every time a dialogue with Kevin comes up. Dialogues seem to play a huge part in the route's progress.
Also I remember answering both the "I think you're cold" and "I don't know" in the shower scene in two separate playthroughs and it both worked. But make sure to save this one in case the other doesn't actually work, good luck!
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So Kevin's route is complex, basically on any day where you don't have an interaction with him just go to bed, this makes triggering the truck repair easier. You have to never apologise in any interaction with him, constantly be upfront with your attraction to him and visit the city instead of the river on the day when you encounter him moving boxes so that you have a third dialogue option on that day. The route has a lot of failure points so if you get to a critical point (fixing the car, shower conversation, camp) and it works save!
In brief: Always go to dinner
Early on know what days you encounter him and on days you don't go to sleep instead of exploring but after the camping trip you can probably stop this.
On day 1 he's patrolling the wall tell him you can't sleep and then say well ok
When he argues with his girlfriend say they woke you up and then go to talk to Norman (should make Kevin fix the car)
On day 8 he's in the bathroom
On day 10 he's on the toilet say what the and then confront him for having the door unlocked (should unlock shower conversation on day 12)
On day 12 he's in the shower say I don't know
On day 13 go to the city instead of the river then talk to him at the locked gate downstairs from the cafeteria
On day 15 do the prank then that night go talk to him in his room and say yes
On day 40 he's in the recreation room opposite the cafeteria (easy to miss him because that room is not normally open)
On day 56 go to the city (easy to miss)