Well if you are in an unhealthy relationship obviously you won't be mentally stable because unhealthy relationships generally involve name calling and rue remarks, and sometimes physical abuse, which would affect your phycial wellbeing aswell.
On the other hand, if you are in a healthy relationship, your health triange would be postivly affected because this person makes you happy if you consider it to be a healthy relationship.
If say they were beating u up it can cause bleeding and bruises and concussions all sorts and even if it’s just say u argue all the time it can cause depression then that depression could lead to u physically or mentally hurting ur self which would cause u to be physically and mentally unstable and if people had seen what u did to ur Sen they could talk to someone who’s worked with people like this and try to help with the depression and the things u did to hurt ur self so it wouldn’t lead u to killing ur self
I do hope nothing is happening to u if so u need to speak to someone in order to seek help