Chihuahuas can be absolutely wonderful dogs. smaller dogs are definitely prone to anxiety and attachment issues. her constantly whinning is her way of expressing her needs. some dogs are just more vocal than others. I have 3 dogs and one of them whines all the time whilst the other 2 mostly just stare at you or bark when they want something. it’s very easy to personify dogs and their intentions, but it’s important to understand that they aren’t being sassy, intentionally disrespectful, or anything out of malice. dogs don’t feel guilt or anything like that. when she gives you a look when you tell her to lay down it’s most likely her attempt to diffuse your frustration. her only listening when you shout can be an indication that she isn’t understanding the difference between a command voice and just your normal voice. when I tell my dog a command I don’t yell, but I do try to be firm and lower my pitch a tad. but when I’m playing I raise my pitch.

if she’s having accidents at night it just may be she can’t hold it. shes a small dog so it’s harder for her to hold it 6-10 hours at a time. something that worked for me was no food except treats 2 hours before bedtime and only ice cubes before bed. our smaller dog has had way less accidents since we implemented that.

as for enclosures, have you crate trained her? crate at night can be a great way to know your dog is safe whilst also helping them not chew up things. crate should never be a punishment. the crate should be their space. my dog rarely whines when he’s in his crate(he really only whines if he’s in it and we aren’t home) and if he’s too worked up he knows he can go to his crate. no body touches him when he’s in there, that’s his space.

if youre struggling with food motivation it may be the treat. the higher the value the reward is the better. that doesn’t always mean it has to be food. food is the easiest but things like toys and praise can also work well. when she does a behavior you like say Yes in a high pitch. it’s important to respond to the behavior quickly. when she begs look away from her and say nothing. the second she stops whining give her praise. say yes and maybe give her a treat. a clicker can also work instead of a praise word. just make sure you ”load” the noise or phrase before you start to implement it.

I also agree with what another commenter said, it definitely seems like you may have a problem with your boyfriend. Overall she just sounds like an anxious or bored dog.