The Catholic Church has allowed priests to bless same-sex couples. The corresponding document was published by the Vatican's Doctrinal Office.
As stated in the declaration, the blessing in such situations is based on the principle that love and mercy from God can be received by all people without exception if they ask for it. Priests themselves must decide in each specific case whether to give a blessing to same-sex couples or not.
Blessings for same-sex couples cannot be given during the liturgy or any other formal church rituals. The priest may, however, read a short prayer asking God to grant those asking for peace, health, mutual assistance, and strength of spirit to fulfill the will of the Lord.
The document emphasizes that the blessing of same-sex couples will not be a legitimization of such relationships from the point of view of the Catholic Church. It also notes that the blessing of same-sex couples cannot take place at the same time as the conclusion of a civil union or if there are clothes or any other visible signs of a wedding at that moment.