I've never had to move on from a mutual love. I've had to move on from several one sided loves. It's such a unique kind of pain when you love someone comprehensively who only loves you in a specific way. For me, it's a kind of pain that never goes away. I just have to have enough other memories to go on top of it to the point where that incident, no longer causes me unbearable pain.
Depends on the reason for the break up. I found out mine didn't want the same things I did, and so I knew the relationship would go nowhere. It doesn't stop you still being in love, it's just the hurt and heartache you need to deal with and eventually you do. But it takes time.