I think some of them marry white and black dudes or Indian or other guys from other nationality. Listed below are some of the reason

1) some nepali guys have commitment issues. (pandeyji)

2) some nepali guys are judgemental and alik dimag ko screw loose wala. (shekhar143)

3) some nepali guys are disrespectful and think nepali girls don't look good. (hanuman1)

4) anti vax wala and full of conspiracy theories (independent)

5) khali bhagwan ko naam line and future predict garna khojne wala (sanaklal)

6) some nepali guys are penny pinchers. I know someone who is such a cheapskate. If he was my husband, I'd have left him so long ago. He controls their money ( his and hers). She has to ask him to buy stuff for her especially online because she doesn't have debit/credit card of her own. She doesn't have a bank account.

7) Some nepali guys are creepy. Bahini bahini bhandai chance payo bhane dance garna khojne wala.