Let's hope for other, better, more harmonious aspects between you, because this one isn't a whole lot of fun. It lends your relationship a feeling of unreliability, as if you just can't trust your partner to be there when you need them. If this tension between you, be it subtle or strong, seems familiar, it's probably not a coincidence -- you may have been lovers in a past life, and this person might have let you down or even broke your heart.
In this life, that old wound still throbs every now and again, and you might notice just the smallest undercurrent of sensation that you shouldn't let your guard down with them. Anytime something unexpected happens between you -- a change in plans for your date, a missed phone call, things of that nature -- you probably have a hard time not concluding the worst. This feeling of distrust could be completely undeserved by your partner. They might behave like a model citizen in this affair, but they might never be able to convince you fully that they really, truly do care about you and that they're really in it for the long haul. Not to mention the fact that with an aspect like this one between you, the long haul could be hard to sustain. Whether this serves as a hard but important lesson in learning to trust each other despite your misgivings, or just makes it too hard to be together as a couple, is really up to you.