Can I obtain a restraining order against a female friend of my husband who is obsessed with calling, texting and sending pictures to him?

You should  speak with an attorney (either personal injury, who  would do restraining orders generally; or a family law attorney, who knows how marriage affects different legal rights) for a definitive answer, but the short answer is that if the calls, texts, pictures, etc. are threatening or harassing, then it may be possible--though it may also be the case that if they only go directly to your husband, that he'd have to be the one to seek the restraining order. However, if they are simply unwelcome and are not harassing or threatening in some way, then probably not; the law does not prevent annoying and unwanted, but otherwise non-threatening, etc., contact. Being someone's spouse does not give you any right to control contact with your husband; again, the issue will be whether the communications rise to the level of being legally actionable, and also who receives them, and thus who is affected by them and therefore has the right to take action.