While you'll try your hardest to hold on to all the things that make you feel secure in life, whatever those might be -- financial security, connections with close friends or family, a stable, committed relationship -- your partner will seek to dismantle every structure you've erected, purely in order to show you that you don't, in fact, need these 'crutches,' as they're likely to think of them. The truth is, they'll be correct, at least to some extent; like everyone, you do rely too much on certain elements to create a false sense of security, because of losses and deprivations you've suffered in past lives. Growing toward a state of elevated understanding about what you truly need to be safe and secure would be a very positive lesson to take from this relationship, except it will require that you face your deepest fears.
If you stay with this person for any length of time, you can be sure that you will face those fears; they won't allow you to keep ignoring them! Their function in your life is to push you to develop a sense of inner security, so that you no longer have to rely on external means to feel stable. But this won't be a fun process. They're likely to push too hard, perhaps even cruelly so, and your fears may grow before they recede once and for all. But know that whatever strength you develop or discover within yourself during this relationship is real -- it's yours to keep. Whether this relationship lasts long-term or not, you'll come through it stronger, and that's a true karmic gift, however it's begotten.