Old story: girlfriend tells the boy to invest more into the relationship. Got me thinking. To make something like this happen in D&D, you'd need some bone for the players to chew on. An advantage.
This subsystem produces a little bit of bookkeeping (mostly the status of the relationship and the xp spent for it) for the DM, but the effort for the players is very minimal, as it should be.
The girlfriend experience (some sort of magic item)
In an ideal world, a relationship helps us to be "better than we are". I asked myself what that means on different occasions. Turns out, it's easier to think about it in terms of D&D.
Let's say we have 3 (+1*) stages in a relationship: (hatred) - indifferent - affected - loved.
Let's further say, those stages are dependend on two other factors: stable and unstable.
To establish an relationship, you need to share. For D&D-characters this means giving up xp (this could also mean treasure-as-xp-the-character-gives-up, like a present) on a regular basis to make this work. It's that or the relationship could fall apart. Like with the man that's always on the road and never talks to his wife. He comes back one day and the apartment is empty but for the little few possessions he owns.
This one is for all those weak-ass characters. 3d6 in a row, heh?
The number of xp (divided by level) a character spends on the first encounter is the percentage to make this an opportunity to go from indifferent to affected. This is modified by circumstances like rivals, cultural differences, whatever a DM could gather (for a rival I'd go with a minus of 10 times hd/level of the competition, for instance). The player never knows for sure, but he might gather intel, of course.
Then the player takes a risk, he has to decide where he gets up to +3 on an ability score**. Why is this a risk, you might ask? If the relationship ends, this will be a negative modifier for the time it hurts. And it hurts as long as it takes to get the experience back that was invested in the relationship (nifty, no?).
This first investment holds (if it works) the stage "affected" for 1d6+3 days stable and after that for the same amount of time unstable (see below for unstable relationships), before it turns back to indifferent. To bring this relationship to the next stage, the player again has to invest xp (divided by level) for the percentage if this is unstable (modifiers might apply here, it's unstable after all) and half of that if it's still stable (no negative modifiers, she's thinking of you...). You made the roll, you are in love (for now). Positive modifiers might be something like proposing (for the time they need to be engaged, see below) or getting her pregnant, to give but two examples.
Keep investing, please...
Now a character has to generate good will to keep the relationship stable. Every time a day is spent as a couple (and 10 xp are given) produces 3 stable days in absence. Tokens of affection given by the character are their worth/10 in days (again, this is treasure that produces no xp for the character, but is given as a present).
The time after that stable period is regarded as unstable and gets a 100% chance minus 5% every day (cumulative and again, modifiers might apply and this means there could be a rival or the character keeps sending messages, something like that) on a d100. As long as it succeeds, nothing happens. This is a DMs duty. He rolls the dice to see how long this stays "love". This ends as soon as the character stops by and shares xp..
The amount of xp accumulated indicates the status of the relationship:
1 0 xp: they are an item
2 500 xp: they are a couple (d100 roll for relationship status gets
a 5% bonus)
3 1000 xp: partner wants to get married (now it's a 10% bonus, if
married, it's a 15% bonus)
4 2000 xp: partner wants children (every child gives an additional
5% bonus on the status roll)
5 4000 xp: the time spend apart without resulting in "unstable" is
6 8000 xp: no idea here, but maybe that's a problem all
relationships face ;)
A character only gets his ability score bonus as long as the relationship is regarded stable
Once the check fails, this goes from "love" to "affected". "Affected" is treated as unstable and starts again with 100% minus 5% per day. If it fails, it's going to "indifferent". If at one point this fails with a roll of 1 (or less) on a d100 (after modification, of course), this might go to hatred faster as usual.
Once the partner is labeled "indifferent", everything could happen. Please roll on the Indifferent Relationship Reaction Table:
2 Hate (character will face hell)
3-5 Dislike (from now on every topic causes an argument)
6-8 Indifferent (needs a second roll a week later)
9-11 Moved on (passive-aggressive behaviour)
12 New love interest (an affair, the character doesnt know)
Every time the d100 has failed with a result of 1 or less, the reaction roll gets a -2. Should this roll produce a negative result, the partner commits suicide.
The day the character realizes that the relationship is over, the pain starts (the positive ability modifier the character chose, is now negative). It hurts as long as it takes to get the experience back that was invested in the relationship.
That's it, so far...
But there is enough room to develop this idea further. Friendships, for instance, could be a light version of this. Or think about the 7 Samurai. A small community depends on the help of strangers and in the end they not only help each other, but form a meaningful connection.
As for the exorcism, this ideas bounced around in my head for some time now and I needed to get them out. I hope there is some sense to it or something useful to loot. Either way, keep the dice rolling...
*That one explains itself later, I hope...
**A spouse/girlfriend/whatever can only boost an ability score she (he) brings to the table herself (hims... you get it). How to find that special someone is matter of another post deep into Reaction Table territory and I work on it. As for now, I want to get this idea out there first.