how did obito get rinnegan

One possibility is that there was some sort of spiritual or chakra - based connection between Naruto and Nagato. Nagato, being the possessor of the Rinnegan, recognized Naruto's strong will and the fact that he was on a path to change the ninja world for the better. Through this connection, Nagato was able to transfer the power of the Rinnegan to Naruto. It could also be related to the nature of the Sage of Six Paths' power that was somehow involved in this transfer, as both Naruto and Nagato were related to the Sage in different ways.

Another possibility is that it's a result of some strange chakra experiment gone wrong (or right). Scientists in the Naruto universe are always dabbling in chakra research. Maybe an experiment meant to enhance her natural abilities instead gives her the Rinnegan, and she then has to learn to control it quickly to avoid being consumed by its power.

In some fanfiction concepts, it might be due to a unique chakra interaction. Maybe the Kyuubi's powerful and ancient chakra somehow triggers a latent ability within Naruto that results in the manifestation of the Rinnegan. It could also be part of some kind of prophecy or destiny within the fan - created world of the story.

He could become more confident, bordering on overconfident at times. With the Rinnegan, he has access to incredible powers, and this newfound strength might make him believe that he can handle any situation alone. However, his friends would surely keep him in check. For example, he might initially rush into a battle thinking his Rinnegan - enhanced abilities will ensure victory without fully considering the risks, but then realize his mistake when his friends point it out.

In some fanfictions, Naruto might get the Rinnegan from Nagato through a transfer of power. This could be due to Nagato seeing Naruto as a worthy successor and using some sort of jutsu to pass on the Rinnegan's power before he dies. Another possibility is that there is some sort of magical or spiritual connection between them that enables the transfer.

Yes, Naruto acquires the Rinnegan in the manga.

Yes, Naruto does obtain the Rinnegan in the manga.

He expressed his love in many ways. For example, he was very concerned about Rin's well - being. Whenever she was in trouble, he would rush to her side without hesitation. He also blushed around her sometimes, which was a sign of his shyness and love for her.

In some fanfictions, Konan might use her origami techniques in a highly lethal way. Maybe she creates a large number of explosive paper bombs and traps Obito in a confined space, detonating them all at once to overpower his defenses and kill him.

In some fanfictions, Naruto might awaken his Rinnegan through a powerful and ancient jutsu. For example, he could come across a hidden scroll that contains the knowledge and power to unlock this dojutsu. Maybe a mysterious sage or an old shinobi reveals the secret to him, guiding him through a series of trials that eventually lead to the awakening of the Rinnegan.