The worst of marriages

Prophet Muhammadصلى الله عليه وسلم said: “The most blessed nikah is the one with the least expenses.” [Bayhaqi]

A) Extravagance 
Firstly we have to look at the weddings of today, the walls are covered, the chairs are covered , the tables are covered but the women are naked. We are the ummah of Muhammad صلى الله عليه وسلم and as such we should follow his example.

So do you want to start the rest of your life in the displeasure of Allah(Ta'ala)? . Ensure that there is a separation between the men and women in your function. You can't control how people dress and you cannot control their gazes but you can ensure that you have tried and your function was not a playground for Zina because of that separation.

If you are spending (on you wedding) to please mankind , you will find them always displeased, you can have the most extravagant , beautiful wedding and you will still find many who were unhappy. You will accomplish nothing by showing off

Secondly Allah (ta'ala) dislikes extravagance 

“…and do not squander wastefully, Indeed, the wasteful are brothers of the devils and the Shaitan is ever ungrateful to his Lord.” (Surah Bani Israel 17:26-27) 

“…the extravagant are the inmates of the fire.” (Surah Momin 40:43)

B) Hassad / Jealousy

“Creeping upon you is the diseases of those people before you: envy and hatred. And hatred is the thing that shapes. I do not say it shapes the hair but it shapes the religion. By the One in whose Hand is my soul, you will not enter paradise until you believe, and you will not believe until you love one another. Certainly, let me inform you of that which may establish such things: spread the greetings and peace among yourselves.”
[Recorded by imam Ahmad and Al-Tirmidhi]

When you spend lavishly to please the people , you will find jealous people from amongst them , they strive in your ruin and because of your happiness their anger and hatred grows even stronger .

We are not saying you can't have a nice function because of people's jealously , we are saying beware of people's jealousy .You spend so much for a few hours and end up regretting for a lifetime when you are being affected by sihr . So be moderate and get married in the pleasure of Allah (ta'lah)

May Allah (ta'ala) grant you'll good , pious spouses who will be a means of your happiness and protect you'll from the evils of this world