Originally posted by Big D
Nope, they were definitely involved, for a while at least. She didn't say she never knew if he felt the same way; but at one point, early on, she wasn't entirely sure if she was completely over him.
I agree - too much is alluded to in the game to pass off Seifer and Rinoa's relationship as anything less than romantic. It is most likely that they had a summer fling and parted amiably - therefore, during the game, there was still unresolved feelings between the two to them.

Originally posted byLockHeart1988

Rinoa didn't seem very upset to me when she heard the annoucement of Seifer being executed. It was like "OMG, Seifer's dead. I think i was in love with him. Oh well, I guess I'll chase after Squall now."
Actually, Rinoa doesn't take it particularly well. When Squall's says that Seifer is dead, Rinoa relpies:
"How can you be so casual? He sacrificed himself for the Forest Owls..."

And when Selphie asks: "Do you still like him?"
Rinoa replies:
"If I didn't, I wouldn't be talking about it. It was last summer...I was 16. Lots of fond memories..."

She also defends his character constantly, like here: "I think...he came to help us - The Forrest Owls. . . I talked about it a lot with him. So please...don't think too badly of him."

I don't get the impression that she is still in love with him, but she still considers Seifer her friend, and she really wants her new friends (including Squall) to accept him as part of her past. And besides, she didn't seriously begin to persue Squall until later in the game - Disc Two, really. I mean, come on, she ditches Squall on the dance floor to go meet up with Seifer.
However, I often argue that during the game, Seifer is still in love with her. It is widely assumed that her connection to Seifer is what got her the meeting with Cid (and thus her prescence at the ball) to have GARDEN aid her resistance group, The Forrest Owls. Seifer obviously pulled some strings for her here, since it is stated that Cid was helping her as a favor since her group couldn't afford to hire SeeDs normally.
Although Seifer would never admit his feelings for her in front of others (in keeping with his tough guy image), he still has a soft spot for her which is often apparent. For example, when he comes after the city leader on disc one, the way he acts towards Rinoa gets Zell's attention:
Zell: "I get it! You're Rinoa's..."
Seifer: "Shut your damn mouth! You chicken!"
I think it is safe to say what Zell was about to say was "boyfriend."
By disc two, when Rinoa's feelings for Squall have strengthened, and overtaken her feelings for Seifer, Seifer begins to show jealousy. In the battle against him at the end of the disc, he gets upset that Rinoa is standing against him with Squall, and says something like:
"Rinoa, what are you doing here? You're gonna fight me, too? Come on, remember a year ago we..."
Rinoa, obviously distraught, interupts him saying, "Stop it!"
He obviously feels betrayed by someone he loved. This sense of betrayal justifies Selfer's violence toward Rinoa later in the game, during the confrontation with Adel. Why would he suddenly hate her so much? Perhaps because by this point, she is pretty much "with" his ultimate rival and his jealousy knows no bounds? Wars have been fought over less. His additude becomes almost, "If I can't have her, no one will." Yeah, there was def. more to them than casual friendship.