We don’t know it with certainty that they are sexually active. The latest “thing” between men these days is “bromance”, and I even read of an example of “bromance” between a straight male and a gay male. These are not sexual relationships.
In ancient times it was not uncommon for males to have deep, intimate relationships with each other, cf David and Jonathan (though the gay rights lobby would have us believe that it was sexual, but there’s nothing to suggest that).
If these “boyfriends” are sexually active, we don’t know the state of their minds nor their place on their walk with Christ. They are perhaps not yet at a point in their lives where they can find the strength and will to end the sexual part of their relationship. Only God knows the state of their hearts and souls, and perhaps their confessors. That applies to all of us and our own habitual sins and temptations.
As the Holy Father said “who am I to judge?”
It’s really quite simple: though we all recognize that sexual activity between persons of the same sex is grave sin, we do not know that they are in fact mortally culpable. If their confessor determines that they are not mortally culpable, then they can quite legitimately receive communion.
Since the seal of the confessional is inviolate, we must thus keep an open mind and allow for the fact that they may in fact not be in a state of mortal sin even if sexually active.