Well, when I learned the Greek types of love, Agape was for people that we did not have a sexual relationship with, since it does include Eros. Agape pretty much is the universal love, the love one has for all human beings.
So, yes, it can have the feelings, like the feelings for a child, but it is deprived of the carnal love.
Therefore, alone, it would not do for a marriage. For a marriage you pretty much need all four types. Agape alone will not do.
It could be put like, Agape exists, or can exist, in a marriage, but a marriage cannot live only with Agape love. So, marital love is composed of the four kinds of love, that together form true love.
Wiki is not so elaborated as University.
And one has to remember that the Greeks would pretty much feel Agapé, and maybe only Agapé, for the spouse since the spouse was not someone they tended to be attracked to. Yes, there were children, but only because they were necessary.
RCR has a view more similar to yours in her article about Agapé. Mine is a little different, since for me Agapé, even if it could be applied to a spouse, only works in a marital relationship if used with the other three.
Otherwise it is the type of love that I feel for my family and that is not the same type of love I used to feel for Mr J.
Sometimes good things fall apart so better things can fall together. (Marilyn Monroe)