How does the poet use symbolism in the poem, They Flee From Me?

Deer symbolize the women who used to love the speaker. He compares the women to deer who were once tamed by him, coming to him willingly to accept the "bread" that he offered from his hand. Now, however, the speaker laments that the women have become like wild deer, roaming free and searching for other tamers (or lovers).

Bread symbolizes love, affection, and sex. The speaker remarks that before their change, the "tame deer" used to come right up to him and eat bread out of his hand. This is a metaphor for what the speaker offered to the women in the past – including affection and sexual satisfaction.