Tangled Heart by Zenina Masters

It’s not easy being green and kept from your tree. Aster is a dryad on a mission to reclaim her own.
Aster was cut off from her tree in a weird turn of events that had her planting her tree in sacred soil and waking a forest god with the power of her oak. Her life was in a static spiral from there.
She joined the human world, started a business, and enjoyed spending her time with trees that grew at her slightest request. Life was good until the fiancée of the fey king contacted her and asked her to join the queen’s court.

Aster thought about joining the fey, and she agreed to do it, on one condition. She wanted to visit her tree.
A flurry of arrangements brings her to the Crossroads, and she confronts the being who had possession of her tree and asks him to let her visit. He says yes on one condition. She has to visit as his mate or the barrier will remain.
She has to think about this.