Green Dot by Madeleine Gray

Hera is in her mid-twenties, which seems young to everyone except people in their mid-twenties.
Since leaving school, she has been trying to kick and scream into existence a life she cares about, but with little success so far.
Until she meets Arthur.
He works with her, he is older than her, he is also married. But in her soulless office - the large cold room she feels destined to spend her life in - he is a source of much-needed sustenance.
And though Hera has previously dated women, she soon falls headlong into a workplace romance that will quickly consume her life.