Wedding Invitations

The groom always uses his full name, preceded by his title.
Abbreviations are rarely used in invitations except for Mr. All other
titles such as “Doctor,” “The Reverend” should always be written out
although Doctor can be abbreviated if the name is exceptionally long.
If it is mentioned again anywhere in the wedding invitation, just be consistent
in the spelling. On the subject of titles, designations such as Ph.D.,
M.D. are not used. Save those for business cards.

It is improper to use initials in wedding invitations. If your
fiancé refuses to use his middle name it would be best to just put his
first and last name and leave out the middle initial. That is the
proper way. As mentioned, however, in my introduction, feelings and
relationships are more important than etiquette, so you may have to
weigh this out if it is an issue.