My favourite was definitely the title story (first two chapters plus the extra at the end). The other two weren't bad, but are the kind of stories you can find in any of the more romantic BL collections out there, so it doesn't matter whether you read them here or not.
Now, onto Doutei Hitsuji to Abazure Ookami. Yes, the romance was fast. But 90% of BL romance is fast, so I don't see a problem; at least this was fast because the uke took the initiative and pursued the seme doggedly until he agreed (not that it took much persuading, lol), which is so much more welcome than the done-to-death "eager-seme-hounding-reluctant-uke" scenario.
The seme is physically weaker than the uke, shy, sensitive, and has old-fashioned ideas of romance. On the other hand, the uke is strong, tall, perverted, and shameless. Tanaka is not one of those creepy seme you find in "less conventional" yaoi, who looks and acts polite/sweet out of bed, but then the moment they get to the topic of sex suddenly turns into a typical slave-to-his-libido manly-man who won't take "no" for an answer -- he's a sweetheart through and through. Is Kira a bit too much? Not in my opinion: it's really refreshing to see a uke who doesn't fake-protest whenever something gets started and is actually the one who initiates most of the situations.
All the praise aside, I wouldn't call anything about their initial meeting or the subsequent development of their relationship "realistic," or "believable." But if you want realistic then what are you even doing reading yaoi (especially oneshots)?
Another thing I loved was the extra, where Tanaka tells Kira how happy he is that Kira has friends who care about him. Far cry from most romances (especially, but not limited to, BL) where we often see one partner get pissed off because his lover is "too popular" and he "wants to keep them to himself." (This is pretty scary, because: dude, you want your BF/GF to be isolated from society and have nobody but you to count on? Sounds like selfish bullsh*t to me) And that note about the beautiful cross-dressing guy being a seme, not to mention the "bonus scene" at the end of the extra, all made for a very amusing reading experience.
I actually saved those three chapters to re-read, which for me and BL is something that happens once every 6 months or so. If you like out-of-ordinary yaoi (especially dominant uke/non-dominant seme) and aren't a stickler for "realism," then I do recommend the title story. If you like romantic yaoi with seme who really care for their uke, then the whole collection is a good option.