I said, turn the question back on them. They already know the answers. If they then ask for your help and support in changing what they can change, that is where you can be a friend.
You ask them why do they think they are. Often it is changeable things like attitude, weight, etc. People know the answers themselves. It is then up to them to change what they can, if they are willing to.
They cannot or are not going to change their personality, so what is the point in telling them you believe that is the reason.
There are personalities I may find repulsive, but people of similar beliefs or personalities may find a common bond with them, and even find them attractive.
Meh, I don't worry about unimportant things. Who gets hurt if your sheets aren't folded perfectly? Who dies if you can't sew? There are more important things in life.
I don't see love that way. I couldn't love somebody just because they make me feel good about myself. Love eithet happens or it doesn't.
I also don't believe in unconditional romantic love. Romantic love is nearly always conditional. To believe it's not could lead to impossible dreams and eventual heartache.
Nobody goes home and beats up their wife, or starts a fight on the street after smoking a spliff. They do after alcohol. It has never killed anyone either, alcohol has. But even with that, it has to be used with respect. Overuse of any drug isn't good. People have to be able to drive, go to work, do all the regular things that people need to do in life rather than spend it in a drug-fuelled happy haze.
RE: Would you tell her/him the truth?
I said, turn the question back on them.They already know the answers.
If they then ask for your help and support in changing what they can change, that is where you can be a friend.