Oxytocin, the so-called love hormone, activates feelings of trust and attraction between people when it is released in the brain, and it rises in the early stages of romantic love. 

Key things to know

• Oxytocin is pretty much fully responsible for the "feeling of love" towards someone.
• It arises in romantic relationships, particularly during the early stages.
• It is responsible for the bonding between mother and newborn child.
• In a monogamous relationship, oxytocin serves both to keep the partners together, and to inhibit interest in other people.
• Oxytocin is involved in the Attachment stage of romantic love.

More References

Love, Actually: The science behind lust, attraction, and companionship [Harvard]

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