Remember Scripture that says who Christ is -- because He is our Rock, and the only relationship that can ground us.
Tell verses like this to yourself:
"The Lord is my Shepherd, I shall not want." "Now you have returned to the Shepherd and Overseer of your souls." (Psalm 23:1, 1 Peter 2:25)
"It is my eager hope and expectation that I will by no means ashamed, but with all boldness, now as always, Christ will be glorified in me, whether by life or by death." (Philippians 1:20)
An excellent exhortation from D. Martyn Lloyd-Jones -
Preach to Yourself
If the talk is about other people's relationships and there's any temptation to jealousy, pray for them, and if you can (if the relationship isn't sinful), thank God for their relationship.