The ruling on one who is prevented from maintaining family ties by an obstacle

Question:
One of my relatives says: "Your greeting is not enough; rather, you must accept my invitation." I am unable to accept his invitation or respond to his call. Am I one who maintains family ties or one who severs them?

Answer:
[al-Taghabun:16], if you are able, accepting the invitation is part of maintaining family ties, responding to the request is part of maintaining family ties, and answering the call is part of maintaining family ties, unless an obstacle such as illness or travel... or if he deserves to be boycotted; then you inform him of the reason that prevents you from maintaining ties with him.
Q: So, is travel an obstacle?
A: There is no doubt about it.