you can support them, as listening to them, letting them talk to you about it.... also, you can tell them that they can always stay at your place or just even visit you if they need to get out of their home. its very important for them that they know they have a safe place to go to when they need to.
Let them know that they can talk to you whenever they need to. Make them feel that your house is a safe place for them to be themselves, a place where they can collect there thoughts. Also let them know that they deserve so much better than what they are going through and that there is so much help out there for her/him with what they are going through.
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