If I tough love you, it means that I actually care. No one wants to be in the position of opposition. Obviously telling someone that they should or should not be doing something is an awkward situation to be in. Yet, if I really care about you, it's the burden that I happily bear in order to best serve you. Of course, it would be easier to agree with you all of the time to keep the harmony, but if I won't be honest with you who will? With the privilege of being this close person to you comes an unwritten obligation and duty to look out for you. I will do it as gently as I can because I don't want to hurt your feelings, but there's no way I am going to lie to you. I'm never going to judge you either.
Only the people closest to you have the right to give you that tough love, and if they aren't keeping you in check then they aren't doing right by you.
If I actually care about you I am going to see your potential even if you can't see it. I'm going to push you to your limit because I believe in you. I am going to push you hard and you are going to hate me at the moment… but then you will be glad you listened to me when you do something out of your comfort zone.
Growth is hard and uncomfortable sometimes, but that's why we call it growing pains.
If I actually care about you, it means that sometimes we are going to argue. That's okay because I also want you to call me out. When you tell me what you really feel, in order for me to achieve what's best for me, I appreciate you keeping me in check. If you tell me something that's hard for me to hear, and hard for you to say I know that you love me. In order for me to improve as a person, I will take a few slaps of reality. We all need constructive criticism sometimes.