‘And Jacob loved Rachel and he said, “I will serve you for seven years for Rachel your younger daughter.” '
Jacob replies that he has made his choice as to which daughter he wants. He is prepared to offer seven years service in exchange for Rachel whom he loves. This may appear a long time but he knows that during the period he will be treated as a relative and equal (‘you are my brother' - Genesis 29:15) and he has brought little with him. Offering service in exchange for a man's daughter was a regular feature of the times.
In fact a period of seven years service appears to have been an accepted one in ‘Hebrew' circles. Consider the stipulations re a Hebrew slave in Exodus 21:2; Deuteronomy 15:12, although the circumstances are not the same. (See article, " ").