I've never heard of Runes of Magic, but I've played World of Warcraft and an old text MMO called Medevia. I understand how these games can suck you in and I've had to take a break at times.
Currently, I play Lord of the Rings Online (LOTRO) and here are some of the things I do to make sure I dont get too involved:
Time / Quest limit - I give myself a time period or a number of quests to fulfill. So I might accept 3 quests to work on which might take me an hour to do. That gives me the satisfaction of making some progress with my toon, while not disrupting family life. I also tend to play on Saturday mornings when the kids are still sleeping in or watching Saturday morning cartoons.
Switch games to something geared for the casual player - I left World of Warcraft, because too many players are WAY too serious about the game. If you miss a raid, they'd boot you out of the guild. I've chatted with a couple of players on LOTRO and we have all said that LOTRO and the people who play it are far more casual about the game than WoW.
Soloing - I also tend to solo more than I do in forms because if my family needs me, all I have to do is find a safe spot and take care of matters. So even if I'm mid-quest, I can easily teleport myself back to a town and log out. I might have to restart the quest, but not a big deal.
Forms - Before I join a party / raid, I ask my wife if it is okay if I play for a longer period of time. Once I join a form, I let them know that I might have to bail unexpectedly and if that is a problem, and it rarely is, as I mentioned, LOTRO seems to be more casual, then I excuse myself politely and let them know that it might not be the right time for me. Everyone is pretty understanding.
Guilds and Kinships - The members of my "kin" / guild are mainly guys in their 30s-40s and we all know that we have real lives. So if we are doing a raid, and someone says that he has to take care of something, we wont go forward in the raid until they are back. In fact our kin broke away from a kin who was lead by this obsessive moron who kept insisting that every player had to recruit, have 2 hours a day on LOTRO, and other silly rules. So about 20 or us said "CYA" and started up our own Kinship.
Believe me I do understand, but if you work at it, it can be a fun diversion rather than an addicting experience.
"Serathir of Area Fifty One" on the Riddermark server