Selphie's relationship with Irvine, Final Fantasy VIII's resident womanizing marksman who cracks under pressure, exposes a fragile side of her that is otherwise well hidden throughout the game, and is therefore very defining of her true character. Selphie is presented to us as an outgoing, laid-back person with an innate ability to socialize with no hesitation whatsoever: Irvine is the first (and only) exception to this rule, turning his role in her life into a very special one.
Although the two of them spent their early childhood together along with the rest of the gang at Edea's orphanage, Irvine is the only one who retains any memories from this period, Selphie and the others having lost theirs due to the side effects of using GFs; unaware that this, and not his perceived irrelevance, was the reason they did not recognize him when the group was first reunited in Galbadia Garden, the fact that he did remember them caused such awkwardness in him that he refrained from mentioning any sort of previous contact with the SeeDs until the flashback scenes in Trabia Garden, already in Disc 2, where he finally lets it all out and even takes the time to comment on how he was especially fond of "spunky little Sefie", the one person back in the orphanage who could make him feel happy just by talking to him
(cheesy, Irvine). Now, as for analyzing, allow me to write a long-ass article on how Selphie deals with these feelings and, as the case may be, responds to them.
First off, let's get this out of the way: Selphie is not an assexual being, nor can she be described as a preadolescent about to reach puberty; if not for anything else, she often calls Laguna a "hunk", just slightly hinting that she feels physically attracted to him
(don't blame you there, Selphie), and that her hormones are doing their job. However, she does not seem minimally interested in the pursuit of romantic relationships of any kind; in her own words, she "just likes being surrounded by lots of friends". Surely, I can imagine her having had several crushes – the whole "OMG LAGUNA'S HAWT" attitude didn't sound like a first –, but the way she reacts to Irvine's "advances" make it clear that she has yet to blossom in the love department. Considering Selphie's happy-go-lucky, carefree view on life and the fact that she doesn't seem to be the type to follow trends (such as dating from a certain age on, yes) or give in to peer pressure, I can easily understand why she would feel satisfied just having fun with the people closest to her: after all, if she has never truly fallen in love, why force anything more serious to happen at all? This, I believe, is the main difference between Rinoa and Selphie: although they often get compared for being optimistic, sociable characters, the former has had more chances to open her heart and let her deeper feelings show, while our Selphie is still rather virginal in this aspect (...and others, I guess).
So, basically, we have Selphie, who, for all her hyper attitude and vivid personality, is very innocent and untouched
(LOL. Okay, I'll avoid the puns from now on) when it comes to love, and this is when Irvine comes in, and... well, ridiculously hits on her, just like he has done with practically every other girl. Strangely enough, out of Final Fantasy VIII's whole female community, Selphie seems to be the only person to actually give his incoherent babbling any importance, and even ler herself be affected by it: "My heart is pounding... What is this I'm feeling?" (...no, Squall, don't answer that). (Besides, you know, for a person like Selphie to say "Y-Yeah right..." instead of "Yeah, right!", a switch somewhere must have been turned on.) I believe this reaction is justified mainly by the fact that our little girl probably never got this kind of attention before; not as persistently, anyway, and not from someone special from her childhood who probably still lingers in her subconscious. Either way, Irvine certainly has his mind set on Selphie, more so than on any other girl, the difference being that this time he actually cares. The first obvious sign of his special fondness happens when Selphie is having a rather bad time, what with Trabia Garden being blown to smithereens destroyed and the Quad stage, which she meant to us for the Garden Festival, rendered useless with the crash against Fishermans Horizon: after trying to get Squall to cheer her up and realizing how stupid this idea had been in the first place (like, Squall? "Cheer up"? WTF?), Irvine decides to do it himself by talking to her and arranging the conditions for her to at least host a concert (hey, it's something). Although she doesn't express her gratitude much more explicitly than usual (not that we know of, anyway...), it is obvious that Selphie is quite thankful for Irvine's actions.
This is closely followed by the flashback scenes mentioned earlier, where, at last, Irvine lets Selphie know how he used to feel about her and (even if indirectly) how he still does. Soon after, Balamb attacks Galbadia and he can be spotted thinking "For me and Selphie!" to himself, which makes it clear that he means every single step towards winning her heart. When put together, all of these events, big or small, seem to amount to something in Selphie's mind, because, from a certain point on, the two of them are seen together a lot more often: they always run ahead together when the party is trying to reach Esthar, Irvine is her co-pilot on the Ragnarok, etc. As time passes, Selphie's attitude around and towards her unconventional Romeo eventually changes: she goes from awkward (implying that, no matter how sociable, she wasn't sure how to deal with these new feelings) to extremely comfortable (enough so for her to wear his trademark cowboy hat and throw an incredibly cute jealousy fit in the game's ending FMV sequence, anyway).
Irvine represents a turning point in Selphie's life: he is the source and catalyst of all the emotions she has been waiting to experience in order to let herself loose, as far as romantic love is concerned. They are serious enough to give each other what they need (Selphie, an actual go at the whole love deal; Irvine, stability and the feeling of being wanted), as should happen in any healthy bond, but not sickeningly dramatic, as most game pairings: in my
humble opinion, they are two wonderful characters who form a lovely, unique spunky duo.
For some weird reason, many people don't seem to consider Selphie and Irvine's a "canon" relationship, which can only mean lack of perception – although it should be universally obvious that
not everyone possesses my emotional IQ it doesn't take explicit dating, kissing or having sex for two people to clearly have something going on.