My girlfriend is part of a very tightly knit church community; I, as an atheist, clearly am not. In the beginning, we thought that this might be a major issue in our relationship, but it hasn't proven to be nearly as problematic as we had feared. The other church members have been almost universally welcoming to me, despite the fact that their faith does not officially sanction same-sex relationships (and is certainly not in support of same-sex marriage). I've eaten meals with church members, cuddled their children, and even attended a few services without bursting into flames. All has gone very well.
Occasionally, however, issues do arise. One of the biggest has been the issue of "small group", which is a group of church members who meet every few weeks to share a meal and discussion of their faith. This is a major social and community event for my girlfriend, as well as for her family, with whom I've grown quite close over the past year and a half. Because the group members discuss things that are going on in their lives (including personal struggles and disappointments), the events are closed to "outsiders" to encourage openness and honesty. Which means that I, the atheist, am not invited.
And sometimes this feels hard. It's difficult to be excluded from something that is so central to my girlfriend's life, especially when all of the other family members (including my girlfriend's new sister-in-law) are automatically included*. And yet, aside from my relationship to my girlfriend, I don't really have a right or a reason to be there. I'm certainly not going to contribute anything to the bible study, and it would only be awkward if the group offered to pray for me after I told them of something difficult in my life. I don't quite know whether I should just accept the status quo, or force myself on a group to which I may not even want to belong.
*Not to mention the food I'm missing out on. Perogies! Farmer's sausage! Baking in all its myriad of forms! These people are amazing cooks.