Believe what you want about missionaries, we have feelings too.
Its hard sometimes, I wont lie... you get to be friends with some of the best people in the world and you have no doubt that you could just talk with them for hours on end. But you always keep your purpose in the back of your mind... you as a missionary are there to share the gospel. You are there in the first place because you have felt these things in your life and seen the positive change and you want to bring that same joy and happiness to those around you. Whatever reasons you had for coming out in the firstplace are void and null once tested... but the reason you stay is because you love the people.
It his the hardest thing to do when you know that there is a good chance that whatever friendly relationship you had will end as soon as you mention the Gospel of Jesus Christ. People don't like to be preached at... people don't like to be told that what they are doing isn't living up to what they could be... people don't like to change.
But we all must change. We all want and need to become something better. All of us fall short, but all of us gotta keep pushing. Our job as missionaries is to invite people to make those changes. My pride and joy is seeing somebody know for themselves that the gospel of Jesus Christ is true, and then do something about it.
On the flip side... it breaks my heart when there is nothing I can do. Sometimes you just gotta let it go, because whatever happens is up to them. We can only help facilitate and provide whatever tools we can to help the person feel the Spirit... we can't do it for them.
But the reason why I do this, the reason why I risk losing friends, is because I care.