I'll give you the guideline:
1. Work at her cafe multiple times. Be supportive to her until you find and choose a dialogue option indicating the start of Amelia Route.
2. Go to Gym multiple times until you get Athlete Trait activated first before you invite Amelia to go jogging ( or morning run ) on every Monday.
3. Invite her to go jogging ( or morning run ) on Monday multiple times until she gives you a blowjob.
4. Then go to the Beach on Friday, have sex with her and tell her that you're falling in love with her.
5. Go to her Cafe the next day and you will get to have sex with her at work as well as Amelia Ending dialogue option.