To pay off student debt: It depends
A lot of people fall victim to crippling student loan debt. If you and your partner need good enough credit, together, to…buy a home…and that can only happen if someone pays off most or all of his student debt ASAP, you may consider helping him out. The question is, however, is he behind on payments? If so, why? Is it due to irresponsible spending? Well then you may want to rethink joining your finances with this person.