There are four kinds of love. Storge, Eros, Phillia, and Agape.
Storge is a parent/child type of love. The love a parent has for a child is insurmountable. It is also explained as a natural affection, for example, how God loves us.
Eros is an intimate, and passionate type of love. This pertains to why you kiss someone. This is the intimate side of love. It comes from the word erotic.
Phillia is a brotherly type of love. It is more of a comradery type of love. A love where you would do anything for them because of how much you love them.
Agape is charity type love. It is a selfless love without intimacy. When you love someone so much that you just want to do things for them and make sure they're okay. It is a lot like an unconditional love.
We need all of these kinds of love to be able to have a successful marriage. If one is lacking then it will cause strain and cracks in the marriage and each other. If we are not careful and this becomes the case then we should find the source of the problem and try to fix it with communication.