The Church has budged on the indissolubility of marriage. It now says according to Amoris Laetitia that two people living in an adulterous relationship which is gravely sinful can be full members of the Church, fully integrated into the life of the Church which includes reception of the Sacraments. It won't be long, if it isn't happening already before the divorced and remarried will be allowed a second Church wedding on the grounds that it is being pastoral to grant this.
The Church cannot have two teachings, one official and the other unofficial which contradicts the official stance.
Science cannot reveal what is moral or immoral. The Church teaches that sex outside of marriage is gravely sinful therefore homosexual activity is always gravely sinful as the Church also teaches that a marriage can only take place between a man and a woman. Science has nothing whatsoever to say on these issues. I'm not sure what you mean by the "expansion of the circle of sympathy".