There is not a lot of good nation-wide data on LGBT topics. Here are a few I was able to find for you. Some of them are already in CSV/TSV and/or Excel format (and therefore trivial to convert to CSV) while some are PDF reports with tables embedded (which, given some effort, could be converted to CSV/TSV tables):
XLS Census/ACS data on same-sex couples: ...
The National Longitudinal Study of Adolescent to Adult Health
This is a tremendously important study, which received a great amount of criticism during its inception and early years. Almost all the data is public and open access.
Still, it was recognized in 2016 with the Golden Goose Award, for a scientific project that keeps on giving.
Pew Research - National Survey of Latinos - "Family, Fertility, Sexual Behaviors and Attitudes"
Data download (requires registration)
Field Dates: 8/5/09 – 9/16/09
Respondents: Nationally-representative sample of 2,012 Latino respondents ages 16 and older
Margin of Error: +/-3.70 percentage points at the 95% confidence level
This survey focused ...
This data is not readily available in the US Census right now. According to this Nov. 2014 story from FiveThirtyEight.com, new questions explicitly asking whether the respondent's spouse was same-sex or different were tested in 2015, but if that happened, presumably it was a limited test. The archived 2015 questionnaire doesn't use the form shown in the 538 ...
Not open data, but relatively easy to register for:
The British National Surveys of Sexual Attitudes and Lifestyles, or Natsal, are among the largest and most detailed studies of sexual behaviour in the world. Three Natsal surveys have taken place to date: Natsal-1 in 1990-1991 (available from the UK Data Archive under SN 3434), Natsal-2 in 1999-2001 (...
Pew Research has a dataset that was used for this article:
A survey of LGBT Americans
You can download the data here, after registering.
Findings in this report are based on two main data sources:
This report is based primarily on a Pew Research Center survey of the LGBT population conducted April 11-29, 2013, among a nationally ...