I live in Canada, so, my opinion might be a little different from others. I personally think saying "mooching" sounds very weird and unnatural. I'd much rather say your second example or "She's been too dependent on me" in a more formal situation.
From where I am, "to mooch" is basically an insult version of "to kiss". So, if you use this verb, it sounds like an insult.
"They always mooch each others' faces in the hallway." (Would be generally considered an insult.)
"They always kiss each others' faces in the hallway." (Depends on context.)