A key mistake that I (F25) have noticed men tend to make is dating outside their "league" for a casual relationship. I know this sub does not permit posts about spefcific situations, but I will illustrate with the following example:

A man (8.5/10) meets a woman (8.5/10) on a dating app. Assume the rating considers all factors. Perhaps the woman is slightly more physically attractive (objectively, not subjectively) than most of the other women the man has dated or slept with. He is still very physically attractive, perhaps an 7 in the looks department, but easily an 8.5/10 when one considers his high income level, educational attainment, stable job, etc.

Initially, the dating goes well. He attempts to impress her by taking her on nice dates, and they fall into bed together within the first three. Both are very attracted to one another. But the woman - perhaps unaware the man is dating others - begins to press for more texting, more meetings etc. He doesn't want a relationship, but he gave her that impression by taking her on nice dates at the beginning. He may attempt tell her he isn't looking for anything serious, but he doesn't want to explicitly tell her that he is seeing others - rather, he wants to give the impression that he would like to take things slow. He therefore attempts to limit communication via text, continue to see her 1x every 2 weeks, etc. Both are very attracted to one another. But the woman - perhaps unaware that the man is dating others - begins to press for more texting, more meetings, etc. He doesn't want to tell her that he's seeing others, of course, because she seems more relationship-oriented. He therefore attempts to limit communication via text, continue to see her 1x a week, yet continue to maintain her high interest level.

Such a situation will never, ever be succesful. An 8.5 man will never be able to maintain the interest level of an 8.5 woman without letting her know that he is seeing other women. Why? Because she wants to see him more, talk to him more etc. whereas he limits this. Letting this fact on not only (a) decreases her attraction level in you, (b) ensures she will never let you go w/o protection, and (c) leads her to begin dating other men (thus making scheduling time with her more difficult). An 8.5 man will not be able to continue casually sleeping with an 8.5 woman indefinetily. Why? Because the woman can casually sleep with men who are 10s indefinetily if she wants to + that is a far better option for her.

Men who find themselves in this situation often begin to lie and tell the woman that she is the only woman they are seeing . . .They treat her like a girlfriend while together - telling her I missed you, I like you, etc. Why? Because that's the only way to keep her interested while limiting the communication by phone.

But telling her that she is the only woman you are seeing is a total mistake - even if its true. Even if she is the only woman you're seeing, if you don't want a relationship, you should never tell her this. Not only will this lead her to ask you for exclusivity, but now, if you decide to take time off (e.g., to go on other dates, add other women to the rotation), she will become suspicious and assume you are dating other women. Now, for some women, this may lead them to become more affectionate/clingy and want to see you more (you may wish to avoid this). Alternatively, it may lead her to pull away completely, and leave you in the dust. Once you state that you are not sleeping with other women, you cannot take the lie back (or do any actions to suggest you may be sleeping with others) without her losing interest in you. You must continue to lie and maintain the same behavior as previously. Even assuming you do maintain the same behavior, she is likely to lose interest because if it is going to remain casual with you, why wouldn't she go be casual with the men who are 10s instead?

Key takeaway is that a man should always attempt to casually date women who are slightly below his league. A man who is a 7 should be dating 5s and 6s, not a 7s. Or, if he does attempt to date those within his league, he must ensure that they are completely OK with being casual. This will ensure that he tell a lie he can never get himself out of.