Such relationships will impact decision making as emotions come into play with command decisions.
Such activity will not be lost on other members of the team, squad, platoon, company, etc. and will effect unit cohesion.
But as you said, that’s a heterosexual issue as well - having a romantic assignation within the squad will effect moral whether it’s guy-girl or guy-guy. So where does that put us? No women in the military either?
Gays in the military brings up a new meaning for “rear guard”