I also think he is saying that love is an ecstatic and illuminating force - that it blasts preconceptions and the blinders of common reality from our eyes - and frees us - although in the power of this experience, it is possible we shall be deceived and hurt - there is risk in this powerful force:
"lawless winged and unconfined"
I think he is not only speaking of romantic love here, but also of the joys of the love of nature, other beings, ideas - enthusiasm and risk generally - and of the transcendence of the spiritual experience of ecsatsy and love.
It gives us wings (is there an echo here of the common image of moths to a flame - I also think of John Donne's famous poem of transcendent love, The canonization:
"Call her one, me another fly,
We're tapers too, and at our own cost die,"
He contrasts this with the cautious, grey, confined, dim world of ordinary existence - of life without the ecstatic and radical force of surrender to love -
Blake is big on the fetters of the customary thought and religion - "mind-forg'd manacles" as he calls them - and the corrupting effect of "civilisation" on human innocence.
Have a look at Songs of Innocence and Experience, for instance.
Here is a critical introduction to Blake which you may like to have a look at - it explores many of his themes and looks at other poems:
Blake is a joy - have a look at more of his work!