Hmmm...my immediate reaction was that LW's use of "girlfriend" -- and the lack of any previous discussion or negotiation -- settled the whole question. At present it's a non-issue. A "girlfriend" is not a business partner. Marriage is a business partnership, legally at very least and most often also in practice. If they were married, it'd be an issue that LW has the right to raise as financial decisions within marriage should be mutual and agreed upon in advance. But their relationship at present is not such that LW has financial rights or claims. LW can raise the issue and ask, but LW is not entitled to anything.

It may be relevant that I am 57 and a straight cis-woman who's lived and negotiated through any number of relationships, married and not, cohabiting and not.