I am an American who is dating a girl from the Philippines. I plan on traveling to see her in a few months. By that time we will have been in the relationship around 8 or 9 months. If we decide to get married over there when I visit (due to the difficulty and expense of traveling back and forth) is the US immigration going to give us problems with the legitimacy of the relationship because, perhaps, they feel our time is not long enough or that I should have visited her several times first? We have no plans on getting married as of yet but the question I ask is relevant to the isse. Thank you for your consideration.

Quotas and requirements change, so you and she need to keep looking on your respective country immigration web sites. When you are visiting her, she can start the application process as a future married person. It doesn't matter how many times you visit.

Have you met her in person before this planned trip?