I need to explain more the reasons indeed

Since this is primarily a strategy game with RPG, the game takes place in a sort of chessboard (who remembers the awesome game Archon for C64?). As each team conquer a "cell", which is a sort of virtual zone in the Limbo, the team increases power.
The heroes though can either teleport or move from the headquarters to the battlefield, but would be practically impossible for plot reasons for the LEADER of the opponent team to "infiltrate" in the enemy base. While a secondary character could come into Lily's base, would still be weird since they're at war
It wasn't an easy decision of course, I would have liked for example Lily Good and Angel (life good), or Ace Good and SuperFoxy (Air good), but I was running out of ideas and budget! is my most expensive game to date, think that just in the first game there are 10 romance ending CGs beside animated backgrounds, battle poses, etc!
In the second/alternate version, Ace's Revenge, you can have different combinations, even if you play as male, there are some that could be interesting I think.