Let's see!
I think the only MU* marriages I have had have been on Firan since marriage was such an integral part of that game. Diamia picked Lucas with her marriage prize and HOOBOY, that caused all sorts of drama (both IC and OOC -- the latter is what prompted Caroline to first start fiddling with the praise/diss code that ultimately got her kicked off staff but that is another story). Didn't actually end up marrying Lucas -- got hitched to Rikon instead which was a very solid relationship both in and out of character. I got along with the player really, really well and we are still friends to this day (I just got back from visiting him actually!) Lucile was married to Daranos briefly before he died; then she had a nice romance with Ryzen and was going to marry him before Custodius murdered him.
I like romance being a part of my RP (and omg, if it can be tragic romance, all the better) but not the whole of it. Its success is largely dependent on my RP partner and if there is even a whiff of OOC possessiveness, then the whole thing sours. Don't pull those kind of stunts, man. I am just here to tell a story, not to be some kind of online surrogate.