Spaghetti ❤️

For the record, the starch in the pasta water acts as an emulsifier- things like carbonara rely on it to keep the sauce from breaking; and it’ll help red sauces to adhere more to the pasta.

As a side note… cook the pasta little under and transfer it to the sauce to finish. (I believe that’s what the other commenter was suggesting,)

Usually I just do a terrible job draining and that’s enough- it doesn’t take a lot;

Using the pasta water for the sauce makes it less runny. YMMV on whether that's a good thing.

I separate the sauce and pasta for a different reason: I cook a large batch and will always have leftovers, so keeping them separated prevents them from spoiling faster (even when refrigerated). An already-mixed spaghetti also gets dry in the fridge compared to heating them separately later on.