I think we have to look at Claudia's age (35) and imagine that many of her peers would have married, started families, maybe moved away from the area.
It's good to see Liz stood by her and will have been interviewed by police due to her contact the night before & long standing friendship, offering an alternative perspective of Claudia.
Here's a link from March 2009 with Liz interviewed in The Spotted Cow pub, Malton "where Miss Lawrence would often visit to catch up with friends and enjoy a drink". She describes her "mental turmoil she was enduring"
Claudia Lawrence case appears on Crimewatch