First, the short answer:

The Ordo Cantus Missae does make the general statement that in Paschaltide one should sing an Alleluia in place of the Gradual. One way to implement that would be to borrow Benedicat vobis, which was the Alleluia for nuptial Masses in the old rite.

Now, some background:

The treatment of Masses pro sponsis in the music books is a little puzzling.

The Ordo Cantus Missae lists two Masses for spouses.

There is the newly invented Ritual Mass pro sponsis: (listed on OCM, p. 130). this is the widely used option in the Ordinary Form.
IN. Deus in loco sancto tuo
IN. Domine, refugium
IN. Timete Dominum
GR. Timete Dominum
GR. Uxor tua
AL. Mittat vobis
OF. Immittet angelus
OF. In te speravi
CO. Beati mundo corde, with verses from Ps. 33
CO. Primum quaerite, with Ps. 36.

And there is the Votive Mass (OCM, p. 168), which is seldom used these days. Perhaps it is offered on anniversaries:
IN. Deus Israel
AL. Benedicat vobis
CO. Ecce sic benedicetur
(no Offertory chant is listed)

The situation is obscured because the votive Mass was not listed in the 1974 Graduale Romanum and the Triplex for some reason.

So if you sing Benedicat vobis, it is still in the official repertoire; you'd be borrowing from the *new* votive Mass for spouses.