In LN I think the priest was an elf who could talk with spirits. Also, MC has a skill called Tsukkomi EX. For example when saw the Demon Lord she used it due to the villain not being a young, beyond human handsome man but a middle aged macho man. Would be happy to know that didn't make much of an impression on rest of party other than a vague mob maid that's utterly average and doesn't leave much of an impression. As for why princess loves prince it's due to the rescue. Hero wanted to return to MC so quickly that he didn't bother defeating the demon generals to release the powerful shield protecting the demon lord's castle but instead called upon the spirits to strike the inside of the shield at the same spot he used a powerful attack on the outside. Then while he dealt with the Demon Lord he had Rufus rescue the princess. Hence to the princess Rufus was the one who came and rescued her while the hero is the one who smashed the castle into bits. As for why the rest of the party is all for it there's two reasons. One is due to having to control his emotions to avoid the spirits picking up on them and causing disasters against whatever irritates him he never was interested in anyone before and want him to be happy. Two, and the main reason, is that due to his connection with all the spirits along with how powerful he is there is no way they can stop him or get in the way even if got everybody in the castle to help so they know it's a fruitless effort to even try.