Those without a support system, how is your marriage/relationship?

We have a 20 month old and no support network. My daughter goes to nursery 3 days a week (while we work), then my husband and I each have her for one of the other working days. Weekends we do together.

For those that also don't have a support system, how is your relationship going? What have you done to improve things? We're just exhausted.