I don’t see anything right now. You’re not likely to find any particularly cheap fares for next summer right now, and you’ll usually pay more by booking two one-way tickets. That said, the cheap one-way to Amsterdam you found is the anomalous good deal. I doubt you’ll find it, but if you’re able to find a similarly priced one-way from Rome it would quite possibly be worth it to book. Otherwise, I’d keep an eye out for multi-city tickets or a even a good deal on a round-trip to AMS and add a cheap flight from Rome to Amsterdam.