A wedding is permitted on Sunday. From the Rite of Marriage:
"11. … If the marriage is celebrated on a Sunday or solemnity, the Mass of the day is used with the nuptial blessing and the special final blessing according to the circumstances. … On Sundays of the Christmas season and in Ordinary Time, the entire wedding Mass may be used in Masses that are not parish Masses."
From The Rites Volume One, Liturgical Press, 1990, ISBN: 0-8146-6015-0, page 722.
Perhaps the issue is how many Masses the priest may celebrate in a day. From the Code of Canon Law, canon 905:
"§1 Apart from those cases in which the law allows him to celebrate or concelebrate the Eucharist a number of times on the same day, a priest may not celebrate more than once a day.
§2 If there is a scarcity of priests, the local Ordinary may allow priests, for a good reason, to celebrate twice in one day or even, if pastoral need requires it, three times on Sundays or holydays of obligation."
(The Code of Canon Law: New Revised English Translation, HarperCollins Liturgical, 1997, ISBN 0-00-599375-X.)
Occasions when a priest is automatically permitted to celebrate Mass twice in a day are given in the 2002 General Introduction to the Roman Missal (GIRM) which can be accessed from romanrite.com/girm.html :
“204. For a particular reason, having to do either with the significance of the rite or of the festivity, the faculty is given to celebrate or concelebrate more than once on the same day in the following cases:
a. A priest who has celebrated or concelebrated the Chrism Mass on Holy Thursday may also celebrate or concelebrate the Evening Mass of the Lord’s Supper;
b. A priest who has celebrated or concelebrated the Mass of the Easter Vigil may celebrate or concelebrate Mass during the day on Easter Sunday;
c. On the Nativity of the Lord (Christmas Day), all priests may celebrate or concelebrate three Masses, provided the Masses are celebrated at their proper times of day;
d. On the Commemoration of All the Faithful Departed (All Souls’ Day), all priests may celebrate or concelebrate three Masses, provided that the celebrations take place at different times, and that the norms established regarding the application of second and third Masses are observed;
e. A priest who concelebrates with the Bishop or his delegate at a Synod or pastoral visitation, or concelebrates on the occasion of a meeting of priests, may celebrate Mass again for the benefit of the faithful. This holds also, with due regard for the prescriptions of law, for groups of religious.”