I am a Christian, not a Muslim. But if more people will view sex as a relationship tool, as opposed to a means to pleasure — an alternative to drugs, alcohol, or other addictions — society would be the much better for it.
Whenever sex occurs in context of a relationship, yet prior to formalization of a relationship, and the relationship breaks down, (in my opinion or worldview) sex is not used wrongly. On the contrary, it is the case that in an imperfect world, sometimes things just do not work out as expected or desired.
Whenever a person lies in order to simultaneously induce both sex and a relationship, however, sex is not a relationship tool. Sex is rooted in deception, is no different from casual sex.
In so far as women looking for sex in context of relationships are concerned, development of awareness as to the extent to which relationship formation only is about sex, as opposed to development of a relationship helps avoid heartaches or heartbreaks.