Neutrally these feelings are hard to scrutinize and get a conclusion out of them as they involve two different extremes of love by crushing you in the middle of an ongoing relationship. These feelings arise when one's relationship is in fragile mode or on the verge of an end due to various possible reasons. It can be right after the honeymoon period or spending more than two years of serious commitment which includes all kinds of adjustments and struggles. This particular phase makes a person weak in one's strong romantic bond and encourages a person to explore by getting rid of relationship knots. Hence one must be aware of such feelings to know whether to get along with them or else to get rid of them.
If you feel happier and have the best time after a long gap with someone interesting in your life and if that's not your partner, then yeah, that other person attracts you better than your current partner. If you get happiness and satisfaction from someone outside of your relationship, just make sure why do you feel like that even after bagging some happy memories with your partner.
Feeling bored seems annoying and it specifies that a particular relationship lost its charm and needs to be rejuvenated as soon as possible. But if that boredom overshadows the love towards your partner and makes you see some other person in light, so that you can bring that glow in your romantic life, then yes, you are surely falling out of your partner and thinking about someone else to take you to shine brighter in your love life.
If you don't feel experimenting with things and making adventures with your partner to spice up your relationship and invest all your time and efforts to impress or make someone else notice you, then deep down you might have lost that connection with your current partner and desperately looking out for someone else to understand your adventurous personality.
When you constantly feel like expressing to open your relationship to allow others to join and make it interesting so that you wouldn't lose your current partner and also can be with someone whom you currently like or love the most. After spending a perfect monogamous relationship, thinking about an open relationship specify your interest in others, be it sexually or romantically.
If you regularly like to not involve your partner in your outdoor parties or events by making plans with someone else, it shows how much you want to spend with others than your partner and if this continues purposely or unintentionally, there are chances that your relationship may end soon.
Feeling for someone else out of your romantic relationship isn't wrong and trying to control your motives towards others than your partner isn't a wrong approach in your dating lifestyle, but you must be clear that those feelings are mere sexual attractions or temporary romantic infatuations, but if you feel more than that, then it's high time for you to accept that you are no more into your current partner and thoroughly want to explore that special someone else.