A friend once told me relationships were all about timing. If it wasn't time then and circumstances tore you apart, maybe it is now. I do think it's a good idea that you're slowing down though. Really take the time to get to know her. People can change a lot over the years. She may not be the same girl you remember. As for the whole obsession thing, this may sound harsh, but it will pass, and hopefully the two of you will fall into a comfortable, relaxed relationship built on trust and stability. I may not be the most qualified person to give relationship advice, but I just think that it's really romantic that this has been going on for the past 25 years or so XD
And yes, not that blood magic is safe at all, but magic really can have a profound impact on your love life. If you two were really willing and determined to be bound forever, well, that's a pretty strong spell right there. If you had the willpower for it, it happened. I hope everything goes well.