Inclusion criteria for Veteran:

1. Be a Veteran (age 18 or older) with a current DSM-5 diagnosis of PTSD (as assessed by the CAPS-5 with a minimum severity score of 25) no less than 3 months after the index trauma occurred (to allow for potential natural recovery)

2. Be on a stable psychoactive medication regimen for at least 4 weeks (if applicable)

3. Be enrolled and eligible to receive care at the VASDHS

   Inclusion criteria for Partner:

4. Be an intimate partner (age 18 or older) who is willing to participate in the intervention (partners can also be Veterans but cannot meet criteria for possible PTSD per the PCL-5)

   Inclusion criteria for Veteran and Partner:

5. Be married, or cohabitating for at least 6 months

6. Willing to be randomized into either treatment condition (bCBCT + OT or bCBCT + PL)

7. Agree to have assessment and treatment sessions audio/video recorded

8. Agree not to receive other individual trauma-focused psychotherapy for PTSD or any form of conjoint therapy during the treatment portion of the study

9. Have the capacity to participate in virtual care (access to internet via DSL or a cable provider, private space)

Exclusion criteria for Veteran and Partner: 10. Current substance dependence in either member of the couple not in remission for at least 3 months, as assessed by the Alcohol Use Disorders Identification Test (AUDIT)74 and Drug Abuse Screening Test (DAST)75 11. Any current uncontrolled psychotic disorder in either member of the couple as assessed by positive screen on the Prime Screen-Revised (PS-R). Exclusion to be determined following case consult by PI or other clinician. 12. Imminent suicidality or homicidality in either member of the couple (e.g., C-SSRS) 13. Any severe cognitive or medical impairment in either member of the couple making it difficult to regularly attend weekly couples psychotherapy 14. Any perpetration of severe physical or sexual relationship aggression (as assessed by the CTS-2) or fear/intimidation (3-item IPV screen, Couples Questionnaire) in the past year

Exclusion criteria for Veteran:

15. Severe ongoing medical problems, including heart disease, uncontrolled hypotension (systolic blood pressure <100 mm Hg) or hypertension (systolic BP >130 or diastolic BP > 80 mm Hg), and neuroendocrinological disorders (e.g., diabetes). Exclusion to be determined in collaboration with study physician following completion of physician's one-on-one appointment with Veteran and review of all relevant information (e.g., risk factors, health history, concomitant medications, etc.) from Veteran's VA medical record and study screening/assessment processes including selfreport measures and blood pressure measurement. Additionally, Veterans for whom the study physician has elevated concern, will be asked to attend an in-person visit at a VA medical center, clinic, or the Veterans Medical Research Foundation before enrollment. 16. Positive screen (7+) for borderline personality disorder (BPD) as assessed by the MacLean Screening Instrument for BPD76. Exclusion to be determined following case consult by PI or other clinician. 17. Pregnancy, delivery in the past 6 months, current breastfeeding, or the ability to become pregnant while not practicing an effective method of contraception. If able to become pregnant, Veteran must have a highly sensitive negative urine pregnancy test verified visually via telehealth or in-person at the Veterans Medical Research Foundation by research staff at study entry and prior to each medication administration during treatment. Veteran must verbally confirm that they completed the test themselves that day. Veteran must also agree to use an effective birth control method from study entry until conclusion of treatment to prevent pregnancy. The ability to become pregnant is defined as: assigned female at birth, fertile, following menarche and until becoming post-menopausal unless permanently sterile. Permanent sterilization methods include hysterectomy, bilateral salpingectomy, and bilateral oophorectomy.

Effective birth control methods include intrauterine device (IUD), injected, implanted, intravaginal, or transdermal hormonal methods, oral hormones, a barrier contraception method (e.g., male or female condoms, diaphragm, cap), or vasectomized sole sexual partner.

Pregnancy tests will be purchased by the study and mailed to Veteran unless PI has approved waiver of testing requirement.

18. Known allergy to preservatives (i.e., Methylparaben, Propylparaben, Glycerin, Sodium Benzoate, Potassium Sorbate, and Disodium EDTA) utilized in oxytocin nasal spray.