Loving the Prophet peace be upon him.
It is part of faith to love Prophet peace be upon him. We believe that he is Prophet of Allah, the seal of Prophethood, meaning he is final prophet and there are no more prophets. Any other people claiming to be prophet is kafir and liars, like muslimah the liar and mirza ghulam ahmed (founder of ahmadiyya and British puppet) may Allah curse be on both of them.
Love of prophet peace be upon him is obtained by following his example that is "Sunnah". Those which are legally prescibed in Quran and Sunnah.
Saying "I love prophet peace be upon him " is not what it meant. Rather it is by action.
Allah says in Quran:
Aal-e-Imran 3:31
قُلْ إِن كُنتُمْ تُحِبُّونَ ٱللَّهَ فَٱتَّبِعُونِى يُحْبِبْكُمُ ٱللَّهُ وَيَغْفِرْ لَكُمْ ذُنُوبَكُمْۗ وَٱللَّهُ غَفُورٌ رَّحِيمٌ
Say, [O Muhammad], "If you should love Allah, then follow me, [so] Allah will love you and forgive you your sins. And Allah is Forgiving and Merciful."
From this verse. Allah tells us to follow His prophet peace be upon him. By following him we are obeying Allah.
Loving Prophet peace be upon him is part of faith. Without it our faith can't be comptele. He said in ahadith:
Hadith
حَدَّثَنَا يَعْقُوبُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا ابْنُ عُلَيَّةَ، عَنْ عَبْدِ الْعَزِيزِ بْنِ صُهَيْبٍ، عَنْ أَنَسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم ح وَحَدَّثَنَا آدَمُ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم
لاَ يُؤْمِنُ أَحَدُكُمْ حَتَّى أَكُونَ أَحَبَّ إِلَيْهِ مِنْ وَالِدِهِ وَوَلَدِهِ وَالنَّاسِ أَجْمَعِينَ "
Narrated Anas:
The Prophet (ﷺ) said "None of you will have faith till he loves me more than his father, his children and all mankind."
Sahih al-Bukhari 15
In-book : Book 2, Hadith 8
USC-MSA web (English) : Vol. 1, Book 2, Hadith 15 (deprecated)
Sahih Bukhari
Hadith
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، قَالَ حَدَّثَنَا عَبْدُ الْوَهَّابِ الثَّقَفِيُّ، قَالَ حَدَّثَنَا أَيُّوبُ، عَنْ أَبِي قِلاَبَةَ، عَنْ أَنَسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ
ثَلاَثٌ مَنْ كُنَّ فِيهِ وَجَدَ حَلاَوَةَ الإِيمَانِ أَنْ يَكُونَ اللَّهُ وَرَسُولُهُ أَحَبَّ إِلَيْهِ مِمَّا سِوَاهُمَا، وَأَنْ يُحِبَّ الْمَرْءَ لاَ يُحِبُّهُ إِلاَّ لِلَّهِ، وَأَنْ يَكْرَهَ أَنْ يَعُودَ فِي الْكُفْرِ كَمَا يَكْرَهُ أَنْ يُقْذَفَ فِي النَّارِ "
Narrated Anas:
The Prophet (ﷺ) said, "Whoever possesses the following three qualities will have the sweetness (delight) of faith:
1. The one to whom Allah and His Apostle becomes dearer than anything else.
2. Who loves a person and he loves him only for Allah's sake.
3. Who hates to revert to Atheism (disbelief) as he hates to be thrown into the fire."
Sahih al-Bukhari 16
In-book : Book 2, Hadith 9
USC-MSA web (English) : Vol. 1, Book 2, Hadith 16 (deprecated)
Sahih Bukhari
Naturally man loves his parents, wife and children. This is shown by his action, how he behave toward them. If his parents order him to take care of them and feed them, after they hsbe turned old and lost much of their strength. Rather than being upset and annoyed, he would always happily take care of them. If his wife wants to have diamond ring. He would alway strive hard to buy it for her, even if he is poor. He would avoid what his wife gets upset by. Same example goes for his children.
So it becomes clear that we shall love Prophet peace be upon him by our actions. Whatever he enjoined us to do good and loves, we shall obey him. We love whatever prophet peace be upon him loved. He loved his companions and family. So we love his Companions and family.
We love whatever Allah and His messenger loves, and we hate whatever Allah and His messenger hates.
Ahmad (18524) narrated from al-Baraa’ ibn ‘Aazib, that the Prophet (blessings and peace of Allah be upon him) said: “Indeed the strongest bond of faith is to love for the sake of Allah and hate for the sake of Allah.”
Any innovations (biddah) can't earn the love of Prophet peace be upon him but it make us astray if we don't stop, while knowing it. So called "mawlid" (prophet peace be upon him birthday) have no basis. Prophet peace be upon him never celebrated his birthday nor his companions and those who succeeded them.
Hadith
حَدَّثَنَا يَعْقُوبُ، حَدَّثَنَا إِبْرَاهِيمُ بْنُ سَعْدٍ، عَنْ أَبِيهِ، عَنِ الْقَاسِمِ بْنِ مُحَمَّدٍ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ قَالَتْ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم
مَنْ أَحْدَثَ فِي أَمْرِنَا هَذَا مَا لَيْسَ فِيهِ فَهُوَ رَدٌّ "
رَوَاهُ عَبْدُ اللَّهِ بْنُ جَعْفَرٍ الْمَخْرَمِيُّ وَعَبْدُ الْوَاحِدِ بْنُ أَبِي عَوْنٍ عَنْ سَعْدِ بْنِ إِبْرَاهِيمَ
Narrated Aisha:
Allah's Messenger (ﷺ) said, "If somebody innovates something which is not in harmony with the principles of our religion, that thing is rejected."
Sahih al-Bukhari 2697
In-book : Book 53, Hadith 7
USC-MSA web (English) : Vol. 3, Book 49, Hadith 861 (deprecated)
Sahih Bukhari