If your boyfriend left a will leaving part or all of his estate to you, you can take action to protect your rights under the will and enforce its terms. But you can only do this if there was a will naming you; without a will, you do not inherit anything, even if you spent money improving his property, since "boyfriend" is not a legally recognized relationship. Only spouses and other family by birth or adoption can inherit; if you were "only" his girlfriend, you have no right to any of his estate and therefore (since you have no rights) you also have no "standing" to take or get involved in any legal action whatsoever. You are entitled to keep your own property (e.g. clothes, jewlery, computer, etc.) at his home; you are entitled to a share of any property or assets which you and he provably owned jointly (in certain kinds of joint ownership, like if you and he owned property as joint tenants with right of surivorship, or JTROS, you might even get the whole asset); but you have no right to anything he owned, which will all go to his children, and do not even have any right to get invovled in the distribution or inheritance of his assets.