Everything is perfect. Birds are tweeting. Frogs are providing a lovely ambiance with their croaking. The full moon sits as a backdrop for your two characters who, after an emotionally-charged love confession, lean in and share their first, perfect kiss.
Why this is bad: This isn’t necessarily bad. Romantic stuff happens all the time in real life. However, first kisses tend to be a lot more awkward than we see it portrayed. People’s teeth clack together, and you don’t each other’s bodies well enough to know when and how to position yourself. Basically, first kisses can be super awkward. So reading about your characters’ perfect experience may read as something more along the lines of wish fulfillment rather than something realistic. First kisses can also happen in very unromantic places, but that doesn’t make them any less meaningful. Having a first kiss means that any romantic tension that you’ve been building up gets almost immediately released.
What you can do to fix it: Make it a little awkward. Especially if neither character is very experienced in the world of kissing, there are going to be some mistakes,and there is going to be some awkwardness. And that’s okay! In fact, it can be endearing to read about two characters going in to mack face and accidentally butting heads. It shows off that element of themselves and keeps them grounded in reality. Also, sometimes it’s nice to have characters in these situations and have them not do anything. I ran into this issue today when I was writing. I built up this marvelously romantic scene, full of gross feeling dumps and tension, all with the intention of them kissing at the end. When I got to the point where I wanted it to happen, I was totally ready. I wanted them to kiss so bad, to finally get all this out of the way and have their feelings plain on the table. Then I stopped. It would be so cliche to have them kiss now, right? Everything is set up for it, the audience is surely expecting it, and if I do it now, all that tension I’ve built up will be for nothing. So, I’ve decided to put it off. I don’t know when they’ll kiss or where, but I know that now isn’t the time.
Bottom Line: Real life is super awkward, so give your characters a semblance of that. Also, readers love unresolved romantic tension (assuming, that is, that you actually resolve it at the end).