It would be incorrect to assume that just because two people of the same sex love each other then that automatically means they must be lesbian or gay. It would be just as bad as automatically assuming that they can't have been lovers because they were in the Bible, and that everyone in the Bible was heterosexual.
The current identity of LGBTs is a relatively recent phenomenon. People classified sexualities differently in the past, e.g. the ancient Greeks classified people as either penetrators (strong, active) or penetrated (weak, passive) - so it was OK to be the penetrator but not the penetrated (women, eromenoi). So it makes no sense to back-project contemporary LGBT identities on to same-sex relationships of the past and/or other cultures. That's why many writers on this subject are careful to refer to "women-loving women" and "men-loving men" when talking about the past or other cultures - becuase then it doesn't assume that the same set of practices and cultural assumptions was happening. Conversely, there's nothing wrong with LGBT people viewing same-gender relationships from the past as inspirational, in fact it's a good thing.
To say that Ruth and Naomi might have been having a sexual relationship is not to "reduce" their relationship to "only" being about sex. Lesbian relationships are not solely about sex - they are also about love, caring, mutual support, friendship, shared values, shared interests, going for walks together, and so on.
It is important not to airbrush out sexuality from texts like the Bible, and ancient mythologies in general. Sexuality is sacred and part of human experience, and it can be deeply spiritual.
It is very important to LGBT Christians to see Ruth and Naomi, David and Jonathan as exemplars of samae-sex love. And I think it quite likely that there was at least an erotic aspect to their relationships. Rev Fred Hammond, a UU minister, points out:
The Hebrew word for love in the text is Ahava. Ahava is used some 250 times in the Hebrew Scriptures. It is used to refer to the sexual as in the very poetic Song of Songs. It is used to refer to the love of a husband for a wife. It is used to refer to passion in illicit relationships. It is used to refer to the love of Jonathan and David, and Ruth and Naomi, and it is used in the great commandment to love one’s neighbor as one self. And while we translate ahava as love, it literally means “I will give.”The word Ahava is just as ambiguous (in the sense of whether it includes a sexual aspect) as our word, love. And this ambiguity leaves it open for a wide variety of ways to express love - and that can only be a good thing.