I agree with keeping things professional and discrete while training. It is important to focus on why you are there and what you want to get out of your training.
I had a relationship with someone at my dojo and it was months before anyone knew about it (that was the way we wanted it). And when it ended it was very difficult, but again, we kept it quiet so as not to disrupt things
with only our closest friends knowing about the break up. However, there was definitely a shift in the energy in the dojo and it has been very difficult to maintain our friendship (tho it is getting better) especially when one or the other begins dating again.
I will say that I would like to date someone who is into Aikido, considering I got into the practice for MY benefit and I spend a fair amount of time training, but I would really only consider seeing someone from another dojo so as not have to go through all the stuff I went through before.
Sharing a common love is important, but being able to do it with someone that has the potential to take you to the next level with it can make it an amazing experience.