"Easy things are tempting, but only if they are forbidden to others." Ovid
The wish to be with one's lover is intense and urgent. However, in some cases blocking this wish and the lover's wish can greatly increase your own desirability. Two ways of doing this are "Playing hard to get" (see here) and "The 'in due course' policy." In both cases, blocking the mutual desire out of long-terms considerations should be selective. The advice of "Don't block everything and don't give everything" is sound.
Why should people adopt the above two policies and prevent themselves and their lovers from kissing, touching, and having sex with each other when they really want to do so?
There may be various reasons for doing this. These include, for instance, moral or religious grounds, as in the case when the two people are not married to each other. Here, I will not discuss the different reasons that lovers might take this course of action; my focus will be on long-term psychological and other considerations. Having sex now might be enjoyable in the short term but harmful in the long term.
Since long-term romantic love might have significant and enduring benefits, genuine lovers should be ready to wait and invest a lot of effort, as well as other resources, in order to attain those benefits. Although 'playing hard to get' ensures that the other person is indeed sincere in his commitment to an enduring relationship, the 'in due course' policy helps to make sure that the lover is mature and serious enough for this intimate relationship. In both cases, love must be "earned" and "proved," often by enduring the pain of separation or by not fully implementing activities associated with romantic love.
The policy of 'playing hard to get' is based on the assumption that if a person is perceived to be unattainable, this fans the flames of love and sexual desire. By forcing a person to invest more effort in obtaining the activities he desires, the activities become more valuable. Moreover, the readiness to invest extra effort in order to enjoy these activities indicates the person's sincere wish to be involved in a long-term relationship.
Playing hard to get is indeed a most effective strategy for attracting a partner (especially when used by women to attract men). However, playing too hard to get is problematic as it may make men think of the woman as "cold," "unfriendly," and "frigid." Accordingly, Walster and her colleagues argue the most desirable woman is a selectively hard-to-get woman, i.e., a woman who is easy for the subject to get but hard for all other men to get. Such a woman incorporates the positive characteristics of a hard-to-get woman - "selective" and "popular" - with the positive characteristics of an easy-to-get woman - "friendly," "warm," and "flexible"; a woman with all of these characteristics is a selectively-hard-to-get woman. A woman can intensify her desirability if she acquires a reputation for being hard-to-get and then, by her behavior, makes it clear to a selected romantic partner that she is attracted to him. This psychological finding is in accordance with the above quotation of the Roman poet Ovid who lived 2000 years ago.
The 'in due course' policy is a more serious attitude (and hence it is sometimes attributed to a sage or a grandmother). This policy does not necessarily doubt the lover's sincerity, but involves waiting until the appropriate time before engaging in full romantic and sexual relationships; that is, when both lovers' attitudes are as mature and serious as is necessary in long-term romantic relationships. Since at the early stage of the relationship, the two people still don't know much about each other, it is doubtful whether they can be certain that their liaison will result in a serious enduring relationship. The love of both should mature and only then should its full implementation take place. The 'in due course' policy constitutes a kind of prolonged courtship. Indeed, marital happiness is positively associated with the length of the courtship period.
Like the situation in the case of 'playing hard to get', the 'in due course' policy also cannot be overly rigid or too long. The progress toward a full sexual relationship should be moderate and indicate to the lover that she does love him but still needs time to realize the seriousness of his love and perhaps hers as well. Indeed, a typical question that arises at the end of this courtship period is whether the lover is serious in his love.
To sum up, both the policy of 'playing hard to get' and of the 'in due course' policy are valuable, although being elusive is mainly of value in the initial stages of the relationship. However, the best circumstances for increasing desirability are when transparency is added as well. Showing selective interest is then the best strategy in both 'playing hard to get' and the 'in due course' policy. Both policies work when they signal selectivity. But for the person you are after, you should be easy to get because otherwise he may doubt your love for him.
The above considerations can be encapsulated in the following statement that a lover might express: "Darling, I know that showing selective interest just in you might make me most desirable to you, but what about fulfilling my desires? Can those be entirely fulfilled by you alone? I doubt it."