It depends on the demand for those tickets - perhaps more Americans want to go to Europe, so the airlines can charge more?
Here is a tip that will help you. The origin of your flight means nothing. It's not where you live, it's not where you are for months before the flight, it's just an airport. And where you fly to is also not where you live or where you are committing to stay the whole time. It's just an airport. So, you want to go SFO-Milan-SFO a lot? Don't throw anything away, just think differently. Let's say you want to spend January, April, and August in Milan.
Look at the price of a one-way ticket SFO-Milan Jan 1st, a one-way ticket Milan-SFO Aug 31st, and a return ticket that combines those two. Buy whichever is cheapest, the two one-ways or the return.
Buy a return ticket Milan-SFO Jan 31st and SFO-Milan April 1st. As though an Italian wants to visit the US for 3 months. Similarly Milan-SFO April 31st and SFO-Milan August 1st.
Presto - you have saved $953*2. In some cases, such as trips for less than a week on airlines that changes less for "Saturday night stays" the savings can be even more impressive. This technique is called "nested returns" and while it's only useful to people who make the exact same trip a lot, it sure is useful. Some people recommend you don't do the first set of tickets (Jan 1 and Aug 31) on the same airline as the others; some say it doesn't matter.