It Costs

From R' Aviner:

Conversation between a father and son:
 "Abba, how much did Imma cost you?"

 "I don't remember! But I am still paying every day…
This is correct. Marriage requires constant effort from both members of the couple. They therefore begin with a down payment: Behold you are betrothed to me with this ring – which must be worth a "perutah" (a minimal amount of money). And one must fulfill, throughout life, what is written in the Ketubah: to feed, cherish, love, etc…
To what is this similar? To an advertisement which boasts of an inexpensive product, but with major payments written in small letters. Similarly, the betrothal is just a "perutah" but the Ketubah contains lengthy payments.
Perhaps you will say that an ongoing payment can be cumbersome. Just the opposite is true! If you exert effort for someone, you will love him or her even more. A general rule of the world is nothing really good is free, and all the more so for the deep connection of marriage.