There are struggles along the way
This a simile. This is because a simile uses like or as to compare two things. A metaphor doesn't use like or as, but it still compares things.
"<span>a.He loved her, and he would love her until the day he was too old for loving—but he could not have her. So he tasted the deep pain that is reserved only for the strong, just as he had tasted for a little while the deep happiness." is the best option, since in this passage it is clear that although he was once fond of love, he has been hurt too many times to feel it take hold of him in the same way.</span>
