In a past life, you two likely had a relationship of nurturer to nurtured; you were their parent or guardian and this person was your child, or perhaps you were a teacher and they were your student. There was a lot of love and care between you then, and it's still there now. They bring you very close together from the start.
You feel bonded and comfortable and your lover feels supported and secure when you're together. All the things that your lover wants in life -- a comfortable income, children someday, a house of your own, maybe a dog or two -- are probably appealing to you as well. You could even be tempted to act on your feelings of familiarity and similarity and made a commitment to each other prematurely. If this has happened, it will probably work out just fine, but you would have been better served to wait and really get to know each other. That's the only trouble with this aspect, though it doesn't really cause much trouble at all: you may not take the time to really get to know each other, because you feel so close so early on that you think you do know each other, through and through. You take your close bond for granted, which could make it difficult when problems or differences start to crop up. So slow down, get to know each other better and have fun together -- that makes the benefits of commitment all the sweeter.