There are no limits on true self-giving. It is not just to those one likes that one makes the offering. This involves a love that issues from the very CENTER of the person's being, directed to the CENTER of the other person's being, a love that gives ALL that the person is in order to foster the other person's life, a love that is offered to EVERYONE, without exception and without condition. The love is not offered to people because they are one's friends; people become "friends" because one loves them.
You come to see that suffering is required; and you no more want to avoid it than you want to avoid putting your next foot on the ground when you are walking. In the spiritual path, joy and suffering follow one another like the two feet and you come to a point of not minding which 'foot' is on the ground. You realize on the contrary that it is extremely uncomfortable hopping all the time on the joy foot.