Learn Italian: Il timore inconscio di soffrire gli fa evitare l'amore. - The unconscious apprehension of suffering makes him avoid love.

Because timore (fear or apprehension) is a noun expressing an emotion or state of mind. In Italian, nouns that express emotions, thoughts, or abstract concepts like paura (fear), speranza (hope), or bisogno (need) almost always require the preposition di to link them to a following infinitive.

Why does the sentence use the indirect object pronoun gli (to him) rather than the direct object lo (him) for 'makes him'?

This is a special rule for the causative construction, which uses fare + infinitive (here, fa evitare). Because the second verb (evitare) already has its own direct object (l'amore), the person being caused to do the action shifts to an indirect object (gli) to avoid having two direct objects in the same clause. If the second verb didn't have a direct object, you would use lo.

Could the adjective inconscio be placed before the noun timore?

It sounds much better after the noun here. Inconscio (unconscious) is a descriptive, categorizing adjective that defines exactly what kind of fear it is. In Italian, adjectives that classify or give objective, defining characteristics almost always follow the noun.

Why is the definite article l' used before when the English translation just says 'love'?