First understand what is a leela (लीला).
In this question -
What exactly is a leela (लीला)? Is there a scriptural definition of leela (लीला)?
Now, the romanticized part of Krishna has been depicted in the scriptures, and therefore it's talked about much. These accounts form the part of bâla-leela (बाल-लीला) of the Lord.
For instance, here's an excerpt which describes Krishna's "romanticism" from the Padma-Purāṇa
Chapter 245, Uttara-Khaṇḍa, Padma-Purāṇa
कामाद्भयाद्वा द्वेषाद्वा ये भजंति जनार्दनम् । ते प्राप्नुवंति वैकुंठं
किं पुनर्भक्तियोगतः ॥ १६८ ॥ तस्य वेणुध्वनिं श्रुत्वा रजन्यां
बल्लवांगनाः । शयनादुत्थिताः सर्वा विकीर्णांबरमूर्द्धजाः ॥ १६९ ॥
त्यक्त्वा पतीन्सुतान्बधूंस्त्यक्त्वा लज्जां कुलं स्वकम् । जगत्पतिं
समाजग्मुः कंदर्पशरपीडिताः ॥ १७० ॥ समेत्य गोप्यः सर्वास्तु भुजैरालिंग्य
केशवम् । बुभुजुश्चाधरं देव्यः सुधामृतमिवामराः ॥ १७१ ॥ ताभिः
सर्वाभिरात्मेशः क्रीडयामास गोव्रजे । तेनापि ताः स्त्रियः सर्वा रेमिरे
निर्भया व्रजे ॥ १७२ ॥ इत्येवं रमयामासुरहन्यहनि केशवम् । वृंदावने
मनोरम्ये कालिंदीपुलिने तथा ॥ १७३ ॥
- to 173. Those who betake themselves to Viṣṇu (even) through lust,
fear or hatred reach Vaikuṇṭha. Then what to say of those who do so
through devotion! Having heard the sound of his flute at night the
wives of the cowherds all got up from their beds with their garments
and hair dishevelled. Tormented by Cupid’s arrows, they left their
husbands, sons, relatives, so also sense of shame and their own
family; they came to the lord of the world. All the cowherdesses,
having approached Govinda, embraced him with their arms, and enjoyed
(i.e. kissed) his lower lip as the gods enjoy nectar. With all those,
the lord of the self sported in Govraja. All those fearless women also
sported with him in Vraja. Thus day after day they sported with Keśava
in the charming Vṛndāvana and the bank of Yamunā.
There's very subtle meanings behind such actions of the Lord, which from the gross understanding level, might look and sound lewd and unworthy.
A similar doubt was raised by goddess Parvati to god Shiva too, on the actions described above.
धर्मसंरक्षणार्थाय जगत्यामवतीर्य सः । परदाराभिगमनं कथं
कुर्याज्जनार्दनः ॥ १७४ ॥
- How would he, Janārdana, who had descended on the earth for the protection of Dharma, approach others’ wives?
Shiva beautifully answers the amorous actions of the lord, as seen from the transcendental perspective as follows -
स्वशरीरे परेष्वंगभेदो नास्ति शुभानने । सर्वं जगच्च तस्यांगं पृथगत्र न
विद्यते ॥ १७५ ॥ स्त्रीपुंभेदो न वै तस्य पुरुषस्य महात्मनः ।
नैसर्गिकस्य भर्तृत्वादात्मेशत्वाज्जगत्पतेः ॥ १७६ ॥ तथापहृतपाप्मत्व
सामर्थ्याद्व्यापिनः प्रभोः । दोषोऽत्र नास्ति सुभगे देवस्य परमात्मनः ॥
- to 177. O you of an auspicious face, he does not differentiate
between his own body and those of others. The entire world is his
body. There is nothing different from it. Due to his naturally being
the lord, the master of the soul and the lord of the world, the noble
one does not recognise the difference between a male and a female. So
also due to his power of removing sins the (all-) pervading lord, the
highest soul, the god, is not at a fault, O fortunate one.
English Translation by N.A. Deshpande
So, Krishna is depicted as a "lovemaker" because it has been described so in the scriptures. But on account of him being Brahman, those are just his divine past times, a sport, a play, without any purpose attached on his volition. It just meant for the spiritual upliftment of the ones in the material world.