"I'll pray for you." It's amazing how differently that phrase can be used.
I see it astonishingly often used as a final "Times infinity!" sure fire put-down line in online 'theological debates' along the lines of "Does!" - "Doesn't!" - "Does so!" There "I'll pray for you" is used to imply - "Whereas I am right in all things and walking in the Spirit, you are clearly blind to the truth of Scripture which I'm so clearly setting out before you and therefore hard of heart to the Spirit of truth, so there is no point me engaging with you further: I'll pray for you." Class dismissed! Probably not truthful and definitely not loving.
I use it disturbingly often well-intentioned but which turns out to be a lie; and I suspect that some others in the world do the same. I'll pray for you: I murmur love and forget it the next minute. I'm working on this: for example, resolving to pray for the person immediately I say the words or read the prayer request, or putting a note in my mobile(!) so to do, so that I don't forget later. "I'll pray for you: hang on while I tie a knot in my trunk! Only as loving as it is truthful.
And then when "I'll pray for you" is welcome: it's real; you know that person is going to sit themselves down with your prayer request and an open Bible and pray for you. Truthful and loving. I thank God for the people I know are doing that for me; I know I need it. I resolve to do it as often as I say it.