Sounds familiar
It is ages since I have been on the website because I sometimes find the subject matter too painful. However, occasionally, as with this topic, I am reminded that there are so many of us coping with the same challenges in life. My mum has a diagnosis of vascular dementia and Alzheimer's and has been in a care home for over 2 years since my dad died. I completely understand what you are saying about leaving a loved one and all I can say is I agree with all of the above. Mum has constantly been a challenge to us when we leave her or if we return her to the home after a trip out, saying she hates it there and wants to come with us. When we have tried to be honest (as per my old mum) she becomes more agitated and cross with us, saying she will go to stay with her mother- my mum is 90! In the same breath she tells us how lovely the staff are with her. So, we have resorted to distraction, giving her a paper to look at, taking her to an activity, the dining room etc.... Or lying as the others have said. I say I am going to places she won't want to go to, say I don't have a car, ask her what she wants from the shops etc... I think we find that whatever works at that time then go with it.
It seems so cruel to fib and totally against how mum and I used to be together, however she is calmer with this approach and it is right for her now. I think to play it low key suits my mum as she is at the moment and it has to be about her and not my feelings. And as someone else said, she will have forgotten that I have been within 15 minutes!
All I can say is good luck and don't be too hard on yourself. Dementia alters the relationship that you have with your loved one but they still have an emotional connection with you which no-one else can offer. They may not be able to express it or even understand it but it is still there. Our visits are precious memories of shared time together.