In this quote, Lawrence Durrell compares love to trench warfare, suggesting that love can be a difficult and uncertain struggle. Just like in war, the presence of challenges and obstacles is felt even if they are not always visible, requiring caution and patience.
The metaphor emphasizes the need for caution and awareness in love, recognizing that while the true difficulties may not always be clear, they still influence the experience. It portrays love as a complex and sometimes perilous endeavor where discretion and self-preservation are wise strategies.