I am at University in the UK and I have lived with friends for 18 months and still do at the moment. For me, it was important to tell my friends what was what just in case anything happened. It made things a bit weird to start with. I felt they were always checking me and watching. But that soon passed. Sure enough, I have had 3 seizures with my friends and they have been really good with me. It was important to ensure my own safety but at the same time, I wanted an element of privacy. Finding the balance was what was important to me. It is slightly different for me as I dont appear to have twinges / auras. Instead I just go down like a sack of spuds!
Its important to tell anyone where your safety is at risk. (For example: If you work with heavy machinery or drive). I also think it is important to have someone who you can always talk to. In this case it sounds like your mum. Keeping things to myself nearly drove me round the bend! lol. For me, the safety of your friends is something that only they can really control. When you are not having a seizure you shouldnt have to worry anyway. When you are, you have no control over what they do. Perhaps this is something that you can advise them about and let them make their own choice; its one less thing for you to worry about. As for relationships, I really can't say anything about this as I have never had one. I don't see how it would be too different to having a good friend.
Hopefully this has been of some help. There are always people here at HW who will listen to you if you get stuck