daughter is in a relationship with an illegal immigrant. can she get into trouble by being with him? How can he be deported?

Your daughter cannot get into trouble by getting into a relationship with an undocumented immigrant. That is, unless she commits crimes with him. In answer to your question as to how your daughter’s boyfriend can be deported, I note that before he is deported, he would be afforded due process under U. S. immigration laws. An undocumented immigrant who is caught up in immigration proceedings may first have his case considered for prosecutorial discretion by ICE, then afforded a hearing before the immigration court if there is no agreement for prosecutorial discretion.  If the decision by the immigration court goes against him, he is entitled to appeal his case to the appellate authority of the U. S. Justice Department and later to the federal courts. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.