How to describe relations that are not good?

• Strained

  William Beckett wrote a song about a strained relationship with her father.

• Tepid

• Lukewarm

• Soured

Consider "tense" for the first question.

tense: marked or causing agitation or uncomfortable feelings.

A tense relationship existed between the two teachers.

For 1.2, I would say they have a stormy relationship.

For 1.3, "hateful relationship" is what comes to mind.

For question #2, I would say their relationship is deteriorating.

deteriorate: to make or become worse or inferior in character, quality, value, etc.

My parents have been married 25 years but their relationship has deteriorated since my brother and I left home.