Here is the full list of all 22 Our Life: Beginnings & Always achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Begin the prologue
Begin the prologue again after playing all the way to the end in a previous file
Start playing Step 1, 2, or 3 using the "nervous" comfort level
Start playing Step 1, 2, or 3 using the "relaxed" comfort level
Start playing Step 1, 2, or 3 using the "direct" comfort level
Start playing Step 1 using the "disinterest" interest level
Start playing Step 1 using the "fond" interest level
Start playing Step 1 using the "crush" interest level
Start playing Step 2 using the "disinterest" interest level
Start playing Step 2 using the "fond" interest level
Start playing Step 2 using the "crush" interest level
Start playing Step 3 using the "disinterest" interest level
Start playing Step 3 using the "fond" interest level
Start playing Step 3 using the "crush" or "love" interest level
During Step 1 tell Cove about the deal his dad wanted to make with you
During Step 2 tell Cove about the deal his dad wanted to make with you
During Step 3 tell Cove about the deal his dad wanted to make with you
During Step 2 confess to Cove that you like him
During Step 3 ask Cove to be your boyfriend or confess to Cove that you're in love with him
During Step 3 give Cove a chance to confess his romantic feelings first
Reach the end of the game
Reach the end of the game after completing it once before