Dear 100 Hour Board,
Is it appropriate to date someone from your mission (investigator, member, another missionary) after you return home? I'd like some quotes from the Brethren on this if you can find any - besides the famous "Lock Your Heart" talk.
I've been searching the archives and haven't been able to find this question, though I feel like someone must have asked it by now. I apologize if there's already an answer somewhere.
I'm not stuck in this kind of a situation, I just talk about it frequently and would like to know if there's any more info on it besides the aforementioned talk.
There are many things the General Authorities leave up to our own agency. This is one of them.
Assuming you were obedient on the mission, why would it not be?
I met a man on my mission who referred to this practice (by which I mean the practice of courting an investigator/convert post-mission; I just noticed you included members and missionaries in your query as well) as "leaving behind your Book of Mormon." As in, "Oh, darn, left my Book of Mormon back in the mission, better go pick it up and maybe see what so-and-so is doing while I'm there..."
Echoing Zed's answer, I doubt there are any official statements on this. I grant that it might seem slightly scandalous to the currently-serving or recently-returned missionary, but really, what does it even matter? You served the mission you served, and there's no way to go back and change it. If you were diligent during your mission, then yes, people are probably still going to be making jokes like "Oh, now I see what you were really focused on when you were there," but you'll know that you did your best, as will Heavenly Father and, likely, the person you're pursuing. If you really did let yourself get distracted while you were serving, well, that's not the best, but again, it's too late to change any of that. Maybe you feel guilty about it, but honestly all I would say is that you should let that motivate you to try harder and do better as you seek to become a spouse and a parent, because I would argue that your success in those areas is ultimately going to be more important than your missionary service.
Anecdotally, I can't think of any instances of a missionary from my mission marrying someone they taught or baptized, but I most definitely have stories of missionaries marrying members and missionaries marrying missionaries. Heck, I think that last one is even encouraged once both parties have finished their missions.
Hope this helps. If I may read into your question a bit, it seems like you may be thinking about retrieving that Book of Mormon, as it were. To which I say: go for it, and let no man or woman dissuade you from your course.
I know a startling number of people who married missionaries and members from their mission. Of those relationships: two missionaries from my mission got married in the temple, one of my old companions went back to my mission and brought a member back to his home country to get married (I think in the temple), and one of my old bishops baptized a woman in his mission then a few years later started dating that girl and eventually married her in the temple.
I'm pretty sure the Brethren don't talk about that as a viable option because missionaries are fasting from romantic love for two years and they will take anything they hear about love and use that to justify actions that may not be helpful to fulfill their mission. It's like wafting brownies in front of someone fasting from food. Honestly, once their mission is over they don't have any restrictions from going back and no responsibilities requiring that romantic fast. I used to be totally against the idea because I've read the "Lock Your Heart" talk too but I've met so many people who have gotten married because they met on their missions that I can only think that there's nothing wrong with it AFTER their mission is over.
My brother married a member that he met on his mission. My adopted sister married someone who was a missionary in the same mission. They all got married in the temple. I think they are all fine.