Are you afraid that by t being with the man you might lose her? If she gets married, has a family, etc she will focus less on you and her clients? Even work less etc?
The reason I ask this is my T became involved in a new relationship a few years ago. While she is too old for children and such, she travels more, is less of a work-a-holic, etc. However, she continues to be a great therapist and such and continues to be there whenever needed.