1. He wants his girlfriend to share his joy: the wedding is an exciting and happy occasion. If a man thinks that his girlfriend will like this occasion and is willing to interact with friends, then taking her to the wedding may just want her to share his joy and happiness.

2. He wants to formally introduce his girlfriend to his friends: if a man has established a stable emotional relationship with his girlfriend and wants to share his life with his friends, taking his girlfriend to the wedding may be a way to formally introduce his girlfriend to his friends. This usually means that he thinks his girlfriend is an important existence and hopes that their friendship can be further consolidated.

3. He wants his girlfriend to know his social circle: a man may think that bringing his girlfriend to the wedding can let his girlfriend know more about his social circle and circle of friends. This kind of understanding helps both parties to communicate and understand better, and also helps girlfriends to better adapt to men's social circles.

He wants his girlfriend to know the possible relatives and friends in the future: at the wedding, men may meet many relatives and friends, who may have an interest in or influence on men's love life. Therefore, bringing my girlfriend to the wedding may also be to give her a chance to meet these possible relatives and friends in the future, so as to better interact and communicate in the future.

It should be noted that the specific reasons may vary from person to person, and the above are just some possible explanations. If you have further questions about the specific situation, it is recommended to communicate directly with your boyfriend to get a more accurate answer.