Again, you are still hung-up on something that has almost no energy in your chart. I have already explained why.
If you insist on looking at rulerships, and trying to figure out marriage by rulerships, then let me show you something that you are not seeing that carries far more weight and interest.
The first house, Libra, is oppose the 7th. Right? This is the difference between ourselves and another intimate relationship, such as marriage or partners.
So, you say that the 7th has no planets. Are you sure?

Doesn't all the planets in the 1st house, and its sign, transfer its energy into the 7th by opposition? So, can't you use all the planets, and all the aspects of all the planets and all the signs of the 1st to see the marriage? Also, the house isn't empty. Pholus is on the cusp of the 7th. Asteroids give some new observations to the chart, when used.
And what is the rulership of the 7th house (not in your chart, but in general)? That would be Libra. What is the planetary rulership of Libra? It is venus. Where is venus? In the third house in your chart. Look at the aspects to venus. So, again, there is more energy happening with these things than the sign on the cusp of the 7th. If you start interpreting the things above, you will begin to get a clearer picture of the marriage, or more accurately, the possibilities of the marriage.
Then, if you want to use rulerships, Aries on the cusp of the 7th. Aries is ruled by the sun and mars. Where is the sun? 3rd house, Sag. Doesn't this give some more information about the 7th house?
Then, if you really want to get detailed or see more, rework the chart. If you want to know about the marriage, re-number your chart. Make the 7th house (the marriage that you are wondering about) and make it the FIRST house. Then, what is actually the 8th house in your chart, becomes the 2nd house, and so on. This will show you how money, the home, children, etc., are likely to be in the marriage. Use all the aspects in those houses as well, but as your interpret, remember that you are not interpreting a person, but an ENTITY (the marriage.)
You see, you are determined to use a kinda skewed idea of rulerships to find the one thing that may (and probably doesn't) affect the 7th house. Then, you ignore all the positive things and further interpretation! For example: isn't it interesting that you first house opposes the 7th house, and the signs are reversed? Aries and Libra? The strength of this combination is amazing! And shows that this is going to be a very important thing for you, in your life. You just aren't going to have problems, despite all the fears you manage to dredge up.
I am not going to do this for you, unless you really need help, but I think you know enough of astrology for these new ways of looking at your chart to keep you busy for awhile. If you other questions, please post.
Cheers...