If you're a fan of oregairu and the amazing writing of yukino and Hachiman relationship just watch this ova to ignore its existence right after because its really just unnecessary drama.
Yui was never a good person, at least as far as a romcom can go, in the main series she was selfish and manipulative, she tried to gaslight Yukino into suppressing her romantic feelings toward her soul mate and tried to snatch him behind her back along many other things so turning into a certified homewrecker is somehow consistent with her subtle yet slimey behaviour and this is the only reason I dont give this ova a 3 rating or lower. Except that Hachiman not insta rejecting her is peak bad writing becasue after an entire series spent building up Hikky and Yukino relationship enphasizing on wanting something genuine just to end up with this unneeded haremesque atmoshphere, talk about something genuine lmao. Komachi trying to sabotage her brother's relationship is also unnecessary and out of character.
Not to mention all the Yukino scenes cut by the source material but at this point we're used to it, hachiman is also far less condeshending in the LN but whatever.
Ah and I wish the studio stopped putting sad music over Yui being a terrible friend.