How many believe that there is more happening on a spiritual/energetic level, that may well interfere with that happy successful relationship?

Hopefully I stated this correctly. We shall see. Thank you for taking the time to rate my profile.

Not entirely sure how you mean that?

I do know from Bruce Lipton (among others) that most people don't really love themselves. When energy tested most test negative to the statement "I love myself".
If you don't, you exude the energy that you are not lovable.
And you repel love. If someone would say "I love you" you would think "How can you love me? Even I don't love myself! You have poor quality control!"
(quoting Bruce Lipton verbatim here)

So in that sense the energy you exude plays a huge role. It is basically everything.

The same goes for self-confidence, healthy boundaries and so on, but in essence these all go back to self-love.

Spiritually, don't get what you mean.
There's nothing or no one spiritually that hinders your quest for love bar (in almost all cases) your own thoughts, beliefs etc.
If you ask (Spirit) it is given.
But if you can't let it in the pressie will stay at the front door.