I really don't think the series needs a season 2. Pretty much everything in the main plot concluded except hints at potential relationships, which honestly, you can't carry a plot with by itself.
Actually the anime skipped quite a few important plot details. The Brunish Civil War may have ended, but the story is far from over. There are some harem elements in the later part of the story, but they don't overshadow the political and war aspects at all. As for Tigre choosing one of the girls, he actually is one of the few harem protagonist with a good reason for not doing that. He's an earl of Alcase and a Knight of Brune. Elen is a War Maiden of Zchted who has to stay in her territory most of the time. Their political affiliations and responsibilities kinda prevent them from getting romantically involved, even though they clearly want to. It also doesn't help that many Brunish nobles suspect Tigre of being in Zchted's pocket. Getting romantically involved with one of their war maidens would certainly not help with this issue.