On the Diotima site search page: http://www.uky.edu/ArtsSciences/Classics/dioquest.html, scroll down and insert the word "marriage" or "wedding" in the "search for" box. Then click on the "search" button. There appear to be many references. The main Diotima page is at http://www.uky.edu/ArtsSciences/Classics/gender.html.
The Teacher Oz Ancient Rome site is at http://members.aol.com/AACTchrOz/romans.html, and it has a section on Women and daily life that has lots of interesting stuff.
The Teacher Oz "Country Information" page at http://members.aol.com/AACTchrOz/countryinfo.html has a section on "wedding customs around the world" including a short page specifically on Italian wedding customs at http://www.weddingcircle.com/ethnic/italian/italian.htm.
The Oz "Middle Ages" page at http://members.aol.com/AACTchrOz/midages.html has a section on Medieval Women including pages on marriage customs (http://www.byu.edu/ipt/projects/middleages/LifeTimes/MarriageCustoms.html) which appear to be mostly English, but also includes Catholic church rules which would also have applied in Italy.
The Oz Renaissance page at http://members.aol.com/AACTchrOz/renaissance.html also has a few pages on Women, but no separate women/family/marriage section.
The Halsall History Sourcebooks at http://www.fordham.edu/halsall/ are always a good starting point, and the Women's history Sourcebook at http://www.fordham.edu/halsall/women/womensbook.html, in particular, may be useful. The sourcebooks link you to texts and other resources on the net.
About.com (which has merged with the Mining.Company) has a women's history guide at http://womenshistory.about.com/education/womenshistory/ It has a marriage subcategory at http://womenshistory.about.com/education/womenshistory/msubmarr.htm.
There is also an About.com "Marriage" guide at http://marriage.about.com/home/marriage/ which has a history subcategory at http://marriage.about.com/home/marriage/msubhist.htm, and that page has a link to a web site concerning marriage in ancient Rome at http://victorian.fortunecity.com/lion/373/roman/romarriage.html as well as other links that are useful on ancient Roman and other marriage customs and laws.
The "Daily Life in Ancient Rome" page has a section on weddings at http://members.aol.com/Donnclass/Romelife.html#WEDDINGS.
There is a page of Internet links on the legal status of women in the Roman World at http://www.uky.edu/ArtsSciences/Classics/wlgr/wlgr-romanlegal.html. Links take you to excerpts from primary sources, and some deal with marriage rights, etc.