There’s a difference between ‘playing it cool’, and behaving in a cool and collected manner in relationships.
If you have an anxious/insecure/preoccupied attachment style (so many of us do!), you may have adopted an attitude of “play it cool” or aloofness in relationships, or defer to your partner’s wishes or desires first, which really comes out as minimizing or repressing your emotions or true desires and needs because of a fear of chasing away your partner or potential mate.
Growing up, or perhaps in an important adult relationship where you felt particularly vulnerable (probably with an avoidant or addicted partner or caregiver), it’s likely it did not feel safe to love and be loved and the attention and affection you were shown was inconsistent and unreliable....so you became insecure and preoccupied with love and your ability to be consistently loved.
Where we lose out by acting in an aloof, play it cool manner is that we never really feel like we are being ourselves in close relationships (because we’re NOT!), nor are we being honest with ourselves or others about what we really want or need. We're acting or reacting from a place of fear of loss and abandonment first as our primary need so we can’t ever really relax into the relationship. We are stuck in a spot of anxious insecurity, because, for us, we desperately want closeness but relationships never feel quite safe enough to express what we really need.
Behaving in a cool and collected manner does not mean dampening down your emotions, desires or needs. It means expressing yourself but not giving in to being reactive, impulsive or resorting to passive aggressive acting out behavior (ie. withdrawing when you feel slighted or hurt as a defense mechanism or to show your partner you are angry without actually saying how you feel, or texting a thousand times when your partner has not responded for half a day).
Calm and collected comes from a place of building inner reliance, security and strength that you learn to own by trusting yourself and knowing yourself deeply. it's possible to lean in and become more secure in relationships. If you are learning that some of your behaviors in relationships or choices in relationship partners are not productive or are leading you into dead end relationship patterns that don’t reflect the amount of soulful love, devotion or commitment your heart really desires, this is likely due to your attachment style. Luckily, there is still time to grow and change these patterns through new awareness.