There are plenty of women, including single moms, who are able to support themselves and their kids. Doctors, lawyers, executives... many single moms, yep.
Frankly, until she is in that situation, she has no business dating. Financial security for herself and her child should be her only priority. Perhaps going to school to get a better life for them if her present job isn't cutting it. The fact she is dating instead of doing these other things should tell you something about her.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh