Obstacle: Death
One of the obstacles Luffy has faced was that heartbreaking and tear-jerking scene were Ace died.
Ace was Luffy's brother, his best friend and one of the many people who encouraged him to be a pirate. Luffy who was also severely injured, was face to face with death, with the help of another pirate from the Worst Generation, Trafalgar D. Water Law ( Surgeon Of Death ). Luffy was still in shock after he woke up, as he started to scream and destroy the things around him, he wants everything to be a dream and denies Ace's death. He is then confronted by a former Warlord ( Jinbei ), who tells Luffy that Ace is dead and that the War was over.
Just before the war started, Luffy was sent to this mysterious island occupied with women, the Empress, Boa Hancock ( also a warlord ), allowed him to stay and took him to Impel Down ( Where Ace was imprisoned, but when he got there, Ace was already on the execution platform ). Luffy was able to rescue Ace from the execution but was unable to stop the former Marine Admiral Akainu ( now Fleet Admiral ) from Killing Ace at the end. Akainu was going to kill Luffy but Ace intervened and was killed instead.
When Luffy returned to the Island of Woman, he was accompanied by Silvers Rayleigh ( he was the Former first mate of the former Pirate King ). Originally Luffy was going to meet up with his crew 3 days later but then Luffy decided to meet up 2 years later.
Luffy wanted to become stronger so he asked Rayleigh if he could train him to become stronger. So he was no longer weak and strong enough to protect the ones around him.'I thought about a way to fight at my fullest. So that I don’t lose anyone… So that I don’t let anyone drift away…' He stayed on an abandoned island for 2 years, perfecting his devil fruit ability, Haki: spiritual energy (Kenbunshoku), life force (Busoshoku) and overpowering enemies (Haoshoku). After the 2 years ( time skip ), he did become stronger, his bounty went from 300,000,000 to 500,000,000 beli.
Luffy also grieved for Ace, his way of getting over Ace's death was an emotional and violent one. As mentioned above, he ran out of Trafalgar's submarine even though he was still injured. He started to destroy the things closest to him, smashing trees, breaking rocks and even destroying the top of the mountain. In the end Luffy had to accept that Ace was dead, but Ace's death drove Luffy to become stronger.
Luffy could of talked to someone about Ace's death, Maybe one of Ace's comrades, they could talk about the happy memories of Aces instead of the miserable ones. Despite feeling upset and guilty, Luffy should of looked after himself, as he was also severely injured. Luffy's first priority was to take care of himself. Losing someone close to us can be extremely hard but it's good to keep in mind that over time, that wound of grief will be healed AND yes, overtime Luffy did get over Ace's death and continued to live his life.
I do think that Ace's death could of been prevented if Ace had listened to Whitebeard, who told them to run back to the ship, and if Ace didn't so worked up about Akainu taunting Whitebeard, everyone knew that Akainu was setting a trap.
