Rav Chaim Volozhiner quoted in Keser Rosh (16) quotes his Rebbe The Vilna Gaon that nowadays the prohibition of Yuharah does not apply nowadays. And that on the contrary, others should see you and learn from you. He only adds that this should be done lishma - for the sake of heaven with pure intentions. But that one should not be worried about others opinions of you.
Though the above Gr”a is not a unanimously agreed upon opinion. I personally have seen many great Scholars learning at the chuppa/other Smachot so as not to waste time, perhaps there actions were based on the Gr”a. The Gedolim that I have personally witnessed are:
Rav Moshe Sternbuch Shlit”a
Rav Asher Arieli Shlit”a
Rav Avigdor Nevenzahl Shlit”a
Rav Yitzchok Berkowitz Shlit”a
Regarding the feelings of the chosson and kallah I think that is very subjective and one cannot presume their feelings. Some may appreciate that people are using their time wisely. Furthermore, it also depends on how conspicuous you are eg. is the book a pocket Sefer that may not be noticed? Or is it a large book that is noticeable to many? Are you standing in the back or in the front? Are you reading out loud or quietly reading? Maybe people will assume you are reading Tehillim, which is very common nowadays to give out parts of sefer tehillim to be said for the zchus of the chosson and kallah
Rav Henoch Leibowitz Zt"l, the Rosh Yeshiva of Chofetz Chaim, in a Hashkafa Shmuess in 1993 said that to learn from a sefer during the Chuppa would be a problem of Yuhara - Overt Haughtiness. Thus he suggests bringing a small inconspicuous sefer to learn from so as not to arouse attention. If this is not possible, one should try to think in learning.