What you ask may or may not spoil the experience for others, so I’m afraid I’ll have to hide this under a spoiler mark. For anyone else who wants to find out on their own, please do NOT check the rest of this post.
Spoilers
There's no romance choices you can make in the game. I'm afraid to say that Lucia has her heart set on someone, and there's nothing you can do to change that (regardless of how it ends). Since you specifically mentioned that this may be a breaker for you, I'll further clarify that this someone is male. And although I'd argue the "romance elements" are fairly minor in this game, that is a subjective appreciation. The fact still stands that most of the important couples in this game (not talking about Lucia here) are male/female pairs, and the motivation of some of these characters are driven by this.I am partial to same-sex romance, but I do not expect it from a game from 2007, so even avoiding romance altogether would be better than the alternative.
You would be surprised, but this is far more common than you seem to think. Perhaps not so much in the big RPG titles that made their way to the west, but it’s still fairly prevalent in the doujin circles. In fact, one of the female characters has a HUGE crush on Lucia, and it’s not implied or “played as good friends” or anything of the sort. Had Lucia been written slightly differently, I wouldn’t be surprised if we saw more Yuri elements in this game, but unfortunately that isn’t the case.