1.: You can meet Dave by working out at the gym frequently. His is the second gym encounter, after Derek’s.
2.: You need to be male and masculine for Dave to want to have sex with you. Once you agree to it the first sex encounter triggers and you can offer to do something other than working out when you meet him at the gym.
3a: Continuing to have sex with him at the gym will result in the ‘fuck machines’ bad end!
3b: You can invite him over to yours to have sex any number of times.
3c: Dave will initially refuse to do anything more with you. You need a level 2 Charm skill for him to tell you why.
4.: Once you know the problem you need to convince Dave that you care. Buy him the correct gift (heart shaped chocolates) in the gift shop to advance the storyline.
5.: Now you can meet Dave at a variety of places around the city. Use your phone to call him and arrange a date.
During this phase you can encounter him at the mall which unlocks the cinema date with him.