In love, you seek a partner who will be sensitive and loyal to you; who will help you create a nurturing safe haven of a home life. Security is of utmost importance to you in a love relationship, followed closely by a warm, nurturing environment, and if you end up with a partner that is cold or untrustworthy, it will really undermine the foundations of your own sense of security and wellbeing. This loyalty can be either sexual or just emotional, or both; but on some deep and important level, you have to feel that your lover is yours, truly, for the long haul.
You have to know that the relationship can withstand the inevitable ups and downs that it will surely go through, if it lasts any length of time at all. And you have to feel certain that your sweetie has your best interests in mind -- that they love you and are taking care of you, as you take care of them. Now, do be careful that you don't get involved in a relationship that demands too much of you on this level. In your urge take care of your sweetie, you might go too far and end up with someone who needs all of your care, but doesn't give enough back. Make sure there is an equal give and take.