Monthly visit visa waiver vs spouse visa for Israel?

I have a what I think is a somewhat unusual question because I can't find anyone else asking about a similar circumstance. My life-partner (we are not married though I would think common law should apply) has applied for a year long program for additional education in her career field at a university in Tel Aviv. She will qualify for the year long student visa. I am not sure how to apply for or if I need a visa to move with her. I am a US airline pilot and have worked out my schedule to work the first two weeks of every month (in the US) with the plan to return "home" to her in Israel when I am off work. How many times in a year can a US citizen enter Israel under the visa waiver? Would I be able to return every 15 days for a year or will they eventually deny my entry? Is there a visa which applies to a situation like this? I myself will not be a student in Israel nor will I be working there. I would prefer paying for an applicable visa for the peace of mind. Thanks in advance.