@Gazni From your answer i will assume your definition of a successfull harem is how you are attract to the girl. So Nisekoi, Gotobun, Oregairu, Oremo, that one show about mc helping 2 girls that best in literature and math, they all have more than 3 girls in the harem and still successfull does it not?

'kindness' does not really connect with 'spinless' man. That just meen he is a good boy, a good man. That all. You can't just judge a mc 'spinless' out of only 8 chapter because he is kind. We haven't even get to know the basic info of all the 7 sins girls yet. No major plot point, no enemy or rival anything. We still in introduction phase. You are too quick on judging. 

As for 'indecisieness', what action give you that impression?

@Gazni Wow first time i heard someone call Toaru series is for po** addict people. Really? Tell me you didn't watch Toaru without telling me you didn't watch Toaru.
"emphasis was clearly on the Miko dressed girl" what wrong with that? DxD emphasis on Rias, Shinmai Maou emphasis on Mio, Sora no otoshimono emphasis on Ikaros. There is no problem with emphasis on a single character at first and than expand out more later. 
Bro, it doesn't matter if these series success for po** addicts or by plot or anything, different author different way, a success is a success. You said "Any harem that has more than 3 girls is doomed to fail as a manga" so i give you example of harem manga that has more than 3 girls got successed. 
Oh and from your first comment, i will assume that you said the mc of this series is spinless or the girls are useless.  Please tell me how the he** did you come up with this when it only been 8 chapter???

@Gazni "Any harem that has more than 3 girls is doomed to fail as a manga"
To love ru, Toaru series, Fate series, High school DxD, Shinmai Maou, Maken-ki, Sekirei, Sora no Otoshimono, many other Harem manga anime that has more than 3 girls and become successfull: 'May be we never existed. Our existence is just an illusion, a myth'

@Yup Yup It's his fiancé

@Heavysaur Well, it depends on each person i guess. You feel it's irritating , but I feel completely normal. I don't see any problem with her behavior, on the contrary I think she did pretty well. Even though she encountered so many strange things, she still tried to stay calm and not dig up the secret of the benefactor who saved her. But if it were me, I probably wouldn't able to keep it that way.

@Heavysaur Because he didn't know about it a day ago??? Have absolutely no idea how to use it and need her to explain it. And a day later he was able to use it naturally. Isn't it suspicious??? It's just a natural reaction. It's like a day ago you didn't know what a gun was. And one day later, you can use it like a pro. If you don't see that as a problem, you should go back and check your logic.

@Goffal Dude, the main character has a 1000 year information gap. Mysterious magic formula. The black sun disappeared. The suspicious appearance of Gram and the Holy Spirit, not to mention that both of them are likely related to the black sun. A girl who looks amazingly like the main character's master. So much mystery, there's nothing wrong with the protagonist being so careful in this case.

@Gazni what marriage?? She goes to the protagonist's territory to investigate the purpose of building an entire military base right next to the border. A military base was built in 2 months without anyone knowing. She estimated it took at least 5000 people to complete this in 2 short months, but when it arrived there were just over 100 people. It was too hard to believe this, so she thought the rest of them had gone into hiding to prepare for a sneak attack. This is a serious issue that could lead to war, and the main character is not serious about it. Everyone in the room was serious, but the main character laughed. She has every right to have such reactions.

@Gazni But she's not a diplomat . She was a warrior, a knight that got promoted to aristocrat. And is in a land that was barren 2 months ago, but now is armed to the teeth by the enemy country by a method that no one knows. It's even close to the border. Manner??? What manner do you want???!!! You bring a child who is considered a prodigy, bring along a few people who can be said to be elites, along with an unknown technology that can build an armed fortress that can hold 5000 soldiers, has a moat, has catapult located right next to the border of the enemy country. From the other side's point of view, it would think the main character's country is flexing its military might. It was lucky that they calm enough to come to investigate and negotiate. That the best manner you can get