The fact is: clinginess extends way beyond infanthood. Every adult has done it at some point in life with a spouse, relative or business partner. Clinginess is simply a form of dependence. So, stop being so dependent on other people! If you are clinging to someone for emotional reasons, such as love or romance, find ways to make yourself emotionally fulfilled.
Focus on loving and romancing yourself instead of clinging to your spouse. Whatever you like to do, treat yourself, whether you like to smell flowers or go out on trips. To stop being clingy means focusing more on yourself and your own needs.