There are various opinions.
1. Because "June" comes from Juno which is a goddess controlling the marriage of the Roman mythology,
The bride will surely find happiness if she marries in the month of this goddess protecting the marriage and women's rights.
2. In Europe, it was forbidden marrying in old days for three months of March and April and May.
Because June was the month when the marriage was lifted, so, many people will get married during June.
3. People choose to get married during June because it has the least rain throughout the year, and it is considered to be good.
In addition, Europeans get into the mood of wedding due to Easter.
Therefore it is said that the bride of June can find happiness!
In Japan, there are some styles of wedding.
Shinto Style Wedding
Christian Style Wedding
Buddhist Style Wedding
In Japan, most young people doesn't have religion.
So people just choose their own wedding with their own liking.