past tense or past continuous tense
In this context, (1) sounds better to me and makes more sense. (2) makes sense too, but I feel the situation being described is trying to convey that the subject was *staring* at her husband (like he's good looking). #1 conveys that. #2 seems to convey more of a momentary situation...like the subject fell because she momentarily looked at her husband.
Both are correct and make equally good sense. They just describe different events. As @ericb says, (1) is a situation and requires the past continuous - she fell down because she wasn't looking where she was going (perhaps); (2) is an event and requires the simple past - she fell down because she was distracted for a moment - "I looked at him". Whichever the speaker chooses will tell a different story.