What is a word for someone who says everything is his unless you pay half of it. My bf and I have been together for 3 years and I always sleep on one side of the bed and so I call it my side and he said that it’s not my side because I didn’t buy the bed. It’s his.
I wouldn't say that there are any exact words to express this idea in English. Usually possession is fairly loose in English. We often use "have" or "my" for association, rather than actual ownership.
As such, one word you could use for him is "Pedantic", which means overly concerned with minor details or rules. "Pedantic" is often used for people who criticize the little things people say (such as "my side of the bed") because of a technicality (real or imagined). Especially if he often corrects little things you say for pointlessly small reasons, "pedantic" is probably a good word to use.
I told my friend to stop being so pedantic after he pointed out my third split infinitive.
Another good word, to point out that he is obsessed with owning things, is "materialistic". Quite simply, he's too focused on material things, and not enough on the important things.
Jack was so materialistic that, when he got into an accident, he cared more about his car than the other people.
I'd suggest that he is being a scrooge (as opposed to Scrooge)
In the English language, a scrooge – with a lowercase “s” – is a person who is unwilling to give to others. Others words with the same meaning are miserly and stingy. Scrooges are selfish, and not just at Christmas time or the holidays. Here is an example sentence: “Her father is such a scrooge."
Are you looking for the word possessive? Oxford Learner's Dictionary defines it as
not liking to lend things or share things with others
Example: Jimmy's very possessive about his toys.
niggardly: [Niggard and nigger wiki are etymologically unrelated words.]
Ungenerous with money, time, etc.; mean.
‘he accused the Government of being unbelievably niggardly’
careless of the rights or feelings of others
‘it's inconsiderate of her to go away without telling us’
Here is an other example,
My boyfriend is a lot of fun and we get on really well, but he can be really selfish and niggardly inconsiderate.