I agree that it can theoretically be done well. The problem with most love triangles is that authors drag them out too long and have them impair the character's judgement to the point where they do stupid things instead focusing on actually important plot points.
But based on the way BS handled the romantic elements in this book, it doesn't seem like he is falling into that last trap. Shallan and Kaladin thought about each other several times, but it was never melodramatic and, most importantly, they didn't dwell on the issue ad nauseam. They had their brief thoughts and then went right back to focusing on the task at hand. If anything, their interactions improved each others judgement regarding the real issues in the plot.
As long as it burns in the background and doesn't stop the characters from focusing on really important things, it shouldn't be that much of a problem. So basically, he should just handle it like he did in this book and all will be fine. Eventually things will have to boil over and be settled, but it's not usually the resolution to love triangle's that is the problem, it's the drawn out, melodramatic build up. He just needs to avoid that.
I actually wanted Shallan/Renarin to happen pre-release....but any chance of it died the moment she called him creepy as far as I'm concerned. Man was that a gut punch, lol.