You can get his 2nd heart after you finished 'I own you a beer' event.
The rest of this I just copy from Wildbara, all credit to them.
- Finish Bandit Attack story, Bandit's Camp morale is 25+.
- Finish Full Moon story, must've checked on Logan first!!!
- Start Bareshade Expansion story, finish the More Houses part.
- Visit the Tavern after 20:00, that triggers the fight between Logan and Barrel.
- Finish Bareshade Expansion completely.
- Finish Country Road story, gained from Ste after inviting him to Bareshade.
- Visit Logan during daytime, witness his outburst, visit Bareshade at night and follow him.
- Help him with work during the day.
- Go to your house in Bareshade at night and Logan will visit you, invite him in, refuse to have sex.