Angels show their love for God through their service of other creatures, just as we are enjoined to show our love for God by serving one another. Angels make God's goodness concrete, both in this life and in the life to come.
Solitude does not necessarily mean living apart from others; rather, it means never living apart from one's self. It is not about the absence of other people, it is about being fully present to ourselves, whether or not we are with others.